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PHYSICAL 

GEOGRAPHY 


BY 

ARCHIBALD GEIKIE, LL.D., F.R.S 

f % 

Director-General of the Geological Survey of the United Kingdom, and 
Director of the Museum of Practical Geology, Jermyn Street 
London ; formerly Murchison Professor of Geology and 
Mineralogy in the University of Edinburgh 


WITH ILLUSTRATIONS 


NEW YORK •: • CINCINNATI •:. CHICAGO 

AMERICAN BOOK COMPANY 

W. P. % 


I ??3 



4 



i 


T ra n sf e r 

0 

Army and Navy Club 

March 3-1931 




PREFACE. 



This little work was written with the object of 
showing that the teaching of science may be based 
- 4 . on practical lessons taken from the common pheno- 
^ mena of everyday experience, and that to stimulate 
habits of observation among pupils is of infinitely 
higher present and future value than to load their 
memories with fact^ of]ben ill understood, and figures, 
painfully remembered. Since its publication in 1873, 
the issue of successive large impressions of the book 
in this country and in America, its translation into 
most European languages, and its introduction as a 
school-book on the Continent, encourage the hope 
that it has in some measure fulfilled its original 
design. It has now been thoroughly revised and 
brought abreast of the onward progress of science. 


November 1883 . 
































































































































































CONTENTS 


Introduction .... 

ART. 

1- 16 

PAGE 

1- 9 

The Shape of the Earth 

17- 27 

9- 15 

Day and Night .... 

28- 39 

15- 19 

The Air— 

I. What the Air is Made of 

40- 45 

19- 22 

II. The Warming and Cooling of the 

Air .... 

46- 62 

22- 28 

III. The Vapour in the Air. Evapor- 

ation and Condensation 

63- 74 

28- 32 

IV. Dew, Mist, Clouds 

75- 82 

33- 37 

V. Rain and Snow . 

83- 90 

37- 40 

VI. The Movements of the Air 

91-102 

40- 46 

The Circulation of Water on the Land 

103 

46 

I. What becomes of Rain . 

104-114 

47- 51 

II. How Springs are Formed 

115-123 

51- 56 

III. The Work of Water Underground 

124-132 

56- 61 

IV. How the Surface of the Earth 

Crumbles away 

133-147 

61- 69 

V. What becomes of the Crumbled 

Parts of Rocks. How Soil is 

Made .... 

148-158 

69- 74 

VI. Brooks and Rivers : Their Origin 

159-174 

74- 81 

VII. Brooks and Rivers : Their Work 

175-186 

81- 88 

VIII. Snowfields and Glaciers . 

187-208 

88-101 

The Sea— 

I. Grouping of Sea and Land.— 

General Features of the Sea 

209-219 

101-106 

II. Why the Sea is Salt . * 

220-223 

106-107 

III. The Motions of the Sea . 

224-237 

108-113 

IV. The Bottom of the Sea . 

238-255 

114-121 

The Inside of the Earth 

256-268 

121-130 

Conclusion .... 

269-270 

130-131 

Questions . 

- 

132-143 


















































































SCIENCE PRIMERS. 

PHYSICAL GEOGRAPHY. 

INTRODUCTION. 

1. Let us suppose that in summer-time a party 
of young people, of whom you are one, have fixed 
upon a certain day for a holiday ramble into the 
country. Some are to gather wild flowers, some to 
collect pebbles, and some are going with no very 
definite aim beyond love of the holiday and of any 
sport or adventure which it may bring with it. 
Soon after sunrise on the eventful day you are all 
awake, and great is your delight to find the sky 
clear and the sun shining. It is arranged, however, 
that you do not start until after breakfast-time, and 
meanwhile you busy yourselves in getting ready all 
the baskets, sticks, and other gear of which you are 
to make use during the day. But the brightness of 
the morning begins to fade. The few clouds that 
were to be seen at first have grown into large heavy 
masses, and seem evidently gathering together for a 


2 


PHYSICAL GEOGRAPHY. 


[iNTROD. 


storm. And sure enough, ere breakfast is well over, 
the first ominous big drops begin to fall. You cling 
to the hope that it is only a shower that will soon 
be past, and you go on with the preparations for the 
journey. But the rain shows no symptom of soon 
ceasing. The big drops come down thicker and 
faster; little pools of water begin to form in the 
hollows of the road, and the window-panes are now 
streaming with rain. With sad hearts you have to 
give up all hope of holding your excursion to-day. 

2. It is no doubt very tantalising to be dis¬ 
appointed in this way, when the promised pleasure 
was on the very point of becoming yours. But let 
us see if we cannot derive some compensation even 
from the bad weather. Late in the afternoon the 
sky clears a little, and the rain ceases. You are 
glad to get outside again, and so we all sally forth 
for a walk. Streams of muddy water are still cours¬ 
ing along the sloping roadway. If you will let me 
be your guide, I would advise that we should take 
our walk by the neighbouring river. We wend our 
way by wet paths, where every tree and hedgerow 
are still dripping with moisture, until we gain the 
bridge, and see the river right beneath us. What a 
change this one day’s heavy rain has made ! Yester¬ 
day, perhaps, you could almost have counted the 
stones, in at least the shallower places, so small and 
clear was the current. But look at it now! The 
water fills the channel from bank to bank, and rolls 
along swiftly. We can watch it for a little from the 


INTR0D.] 


PHYSICAL GEOGRAPHY. 


3 


bridge. As it rashes past, innumerable leaves and 
twigs are seen floating on its surface. Now and 
then a larger branch, or even a whole tree-trunk, 
comes down, tossing and rolling about on the flood. 
Sheaves of straw or hay, planks of wood, pieces of 
wooden fence,—sometimes a poor duck, unable to 
struggle against the current,—roll past us, and show 
how the river has risen above its banks and done 
damage to the farms higher up its course. 

3. We linger for a while on the bridge, watching 
this unceasing tumultuous rush of water and the 
constant variety of objects swept down the channel. 
It was perhaps almost worth while to lose the 
holiday for the sake of seeing so grand a sight as 
this angry and swollen river, roaring and rushing 
with its full burden of dark water. Now, while the 
scene is still fresh before us, let us ask ourselves a 
few simple questions about it, and you will find 
perhaps additional reasons for not regretting the 
failure of the promised excursion. 

4. In the first place, where does all this added 
mass of water in the river come from ? You say it 
was the rain that brought it. Well, but how should 
it find its way into this broad channel 1 Why does 
not the rain run off the ground without making any 
river at all 1 

5. In the second place, where does the rain come 
from 1 In the early morning the sky was bright, 
then clouds appeared, and after that came the rain. 
You answer that it was the clouds that supplied the 


4 


PHYSICAL GEOGRAPHY. 


[INTJROD. 


rain. But whence come the clouds, and how do they 
gather rain and let it descend upon the earth ? 

6. In the third place, what is it which causes the 
river to rush on in one direction more than another ? 
When the water was low, and one could, perhaps, 
almost step across the channel on the stones and 
gravel, the current, small though it might be, was 
still quite perceptible. One could see that the water 
was moving along the channel, always from the same 
quarter. And now when the channel is filled with 
this rolling torrent of dark water, you see that the 
direction of the current is still the same. Can you 
tell why this should be ? 

7. Again, yesterday the water was clear—to-day it 
is dark and discoloured. We take a little of this 
dirty-looking water home with us, and let it stand 
all night in a glass. To-morrow morning we shall 
find it clear, while a layer of fine mud will have sunk 
to the bottom of the glass. If we shake the glass 
and stir up the mud the water becomes dirty, as 
it was in the river. It is mud, therefore, which 
discolours the swollen river. But where did this 
mud come from? Plainly, it must have something 
to do with the heavy rain and the flooded state of 
the stream. 

8. Well, this river, whether shallow or in flood, is 
always moving onward in one direction, and the mud 
which it bears along is carried towards the same 
point whither the river itself is hastening. While 
we sit on the bridge watching the foaming water as 


INTROD.] 


PHYSICAL GEOGRAPHY. 


5 


it eddies and whirls past, the question conies home 
to us—what becomes of all this vast quantity of 
water and mud ? 

9. Kemember, now, that our river is only one of 
many hundreds which flow across this country, and 
that there are thousands more in other countries 
where the same thing may be seen which we have 
been watching to-day. They are all in continual 
motion, are flooded when heavy rains come, and 
carry more or less mud along with them. 

10. As we walk homewards again, it may be well 
to put together some of the chief features of this 
day’s experience. We have seen that sometimes the 
sky is clear and blue, with the sun shining brightly 
and warmly in it; that sometimes clouds come across 
the sky, and that when they gather thickly rain is 
apt to fall. We have seen that a river flows; that 
it is swollen by heavy rain; and that when swollen 
it may be very muddy. In this way we have learnt 
how close is the connection between the sky above 
us and the earth under our feet. In the morning it 
seemed but a little thing that clouds should gather 
overhead; and yet, ere evening fell, these clouds led 
by degrees to the descent of torrents of rain, the 
flooding of the river, the sweeping down of trees, 
fences, and farm produce; and it might even be to 
the destruction of bridges, the inundation of fields, 
villages, and towns, and a large destruction of human 
life and property. 

11. Those who live in a large town and have no 


6 


PHYSICAL GEOGRAPHY. 


[iNTROD. 


opportunity of seeing country sights, naturally enough 
imagine that these things cannot have much interest 
for them, and that they have no chance of seeing 
with their own eyes how nature works. They are 
not, however, without their opportunities. For 
example, they may learn a great deal about rain and 
streams even in the streets of a town. A little of 
the rain caught in a plate is so much clear water. 
But as it courses along the gutters, how muddy it is ! 
It has swept away the loose dust worn by wheels 
and feet from the stones of the street. Each gutter 
thus becomes like the flooded river. One can watch, 
too, how chips of straw, corks, bits of wood, and 
other loose objects lying in the street, are borne 
away, very much as the trunks of trees are carried 
by the river. Even in a town, therefore, we can 
observe how changes in the sky lead to changes on 
the earth. 

12. If you think for a little, you will recall many 
other illustrations of the way in which the common 
things of everyday life are connected together. As 
far back as you can remember, you have been familiar 
with such things as sunshine, clouds, wind, rain, 
rivers, frost, and snow, and they have grown so 
commonplace that you never think of considering 
about them. You cannot imagine them, perhaps, 
as in any way different from what they are; they 
seem, indeed, so natural and so necessary that you 
may even be surprised when any one asks you to 
give a reason for them. But had you lived all your 


INTEOD. ] 


PHYSICAL GEOGRAPHY. 


7 


life in a country where no rain ever fell, and were 
you brought to such a storm of rain as we have been 
watching to-day, would it not he very strange to you, 
and would you not naturally enough begin to ask 
the meaning of it ] Or suppose that a boy from 
some very warm part of the world were to visit a 
country in winter, where he could see, for the first 
time, a shower of snow, and rivers solidly frozen over, 
would you be surprised if he showed great astonish¬ 
ment 1 If he asked you to tell him what snow is, 
and why the ground is so hard, and the air so cold, 
—why the streams and ponds have become crusted 
with ice,—could you answer his questions 1 

13. And yet these questions relate to very com¬ 
mon everyday things. If you think about them 
you will learn, perhaps, that the answers are not 
quite so easily found as you had imagined. Do not 
suppose that because a thing is common, it can have 
no interest. There is really nothing so common as 
not to deserve our attention, and to reward us for 
trying to understand it. 

14. In the following pages I propose to ask you 
to look at some of these common things. You 
must not think, however, that it is my wish merely 
to set certain lessons which must be learnt, and to 
give a list of names and figures which must be 
committed to memory. My object rather is to urge 
you to look around, and to think out as far as you 
can the meaning of what you see. I would fain 
have you not to be content with what is said in 


8 


PHYSICAL GEOGRAPHY. 


[iNTROD. 


this little book, or in other books, but rather to 
get into the habit of using your own eyes that you 
may see and understand what takes place in this 
wonderful world of ours. All around there is abund¬ 
ant material for this most delightful inquiry. No 
excursion you ever made in pursuit of mere enjoy¬ 
ment and adventure by river, heath, or hill, could 
give you more hearty pleasure than a ramble with 
eyes and ears alike open to note the lessons to be 
learnt from every day and from every landscape. 
Remember that besides the printed books which 
you use at home or at school, there is the great 
book of Nature, wherein each of us, young and old, 
may read and go on reading all through life, with¬ 
out exhausting even a small part of what it has to 
teach us. 

15. It is this great book—Air, Earth, and Sea— 
which I would have you look into. Do not be con¬ 
tent with merely noticing that such and such events 
take place. For instance, to return to our walk to 
the flooded river: do not let a fact such as a storm 
or a flood pass without trying to find out something 
about it. Get into the habit of asking Nature ques¬ 
tions, as we did in the course of our homeward walk. 
Never rest until you get at the reasons for what you 
notice going on around you. In this way even the 
commonest things will come to wear a new interest 
in your sight. Wherever you go there will be some¬ 
thing for you to notice,—something that will serve 
to increase the pleasure which the landscape would 


INTKOD.] 


PHYSICAL GEOGRAPHY. 


9 


otherwise afford. You will thus learn to use your 
eyes quickly and correctly; and this habit of obser¬ 
vation will he of the utmost value to you, no 
matter what may be the path of life that lies before 
you. 

16. In the following Lessons I wish to suggest the 
sort of questions you may put about some of the chief 
parts of the book of Nature, and especially about two 
of these—the Air and the Earth. Each of us should 
know something about the air we breathe and the 
earth we live upon, and about the relations between 
them. Our walk showed us a little regarding these 
relations when it enabled us to connect the destruc¬ 
tion of fences and farms with the formation of clouds 
in the sky. Many other relations remain for you to 
find out. In tracing these you are really busy with 
science—with that branch of science called Physical 
Geography, which seeks to describe this earth, with 
all the movements that are going on upon its sur¬ 
face. And yet you are not engaged in anything very 
difficult or uninteresting. You are simply watching 
with attentive eyes the changes that are continu¬ 
ally taking place around you, and seeking to find 
out the meaning of these changes, and how they 
stand related to each other. 

THE SHAPE OP THE EARTH. 

17. Before observing what takes place on the 
surface of the earth, it may be well to form a clear 
B 


10 


PHYSICAL GEOGRAPHY. 


[shape of 


notion about the shape of the whole earth as a mass, 
and to fix in the mind some of the great leading 
features of the connection between the earth and 
the sun. 

18. When one stands in the middle of a broad 
flat country, or looks out upon the wide sea, it seems 
as if this world, whereon we live and move, were 
a great plain, to the edge of which one would come 
if one went far enough onward. This is the first 
notion we all have as children. It was also the firm 
belief of mankind in early times. The sun and 
moon were once thought to rise and set only for the 
use of the human race; and the sky, with all its 
stars, was looked upon as a great crystal dome cover¬ 
ing and resting upon the earth. 

19. But we can easily prove to ourselves that the 
eye is deceived about the flatness of the earth, and 
that what seems quite level is in reality curved. In 
a wide level country, one cannot see trees and houses 
farther away than some four or five miles. If we 
climb to the top of a church-tower, we find many 
objects come into sight which could not be seen from 
the ground. And if there happens to be a range of 
hills in the neighbourhood, we can note from their 
tops a still larger number of points that before were 
hidden. The higher one climbs above the ground, 
therefore, the farther one can see. 

20. Again : suppose you were placed by the shore 
of the open sea, at the bottom of a tall cliff, and on 
looking seaward were to note the sails of a distant 


THE EARTH. ] PHYSICAL GEOGRAPHY. 


11 


ship. If you mounted to the top of the cliff, you 
might see not only the sails, but the whole vessel, 
and your eye would probably pick out ships still 
farther away, appearing as mere specks along the 
line of meeting between sea and sky, and which 
could not be seen at all from the beach. 

21. Suppose, further, that from the top of that 
cliff you watch these vessels for a time. Some of 
them, which at first were so far away as to be scarcely 
visible, would probably seem to grow bigger and 
clearer. You would begin to make out the tops of 
the masts and sails; by-and-by the rest of the sails 
would appear, until at last the hulls too came into 
sight. These vessels would seem to you to have 
sailed up over what used to be thought the edge of 
the world. 



Fig. 1.—Disappearance of a Ship at Sea owing to the curved surface of 
the Earth. 


22. On the other hand, some of the ships which 
were near you at first will gradually sail away into 
the distance. Their hulls will dip down into the sea, 









12 


PHYSICAL GEOGRAPHY. 


[shape of 


as it were ; then the sails will slowly sink, and in the 
end all trace of the vessels will have vanished. 

23. Now, in making these observations, you will 
have gathered facts which prove that the world we 
live in cannot be a flat plain. Had it been so, the 
hulls of the vessels would not have sunk out of 
sight. Their appearance and disappearance, accord¬ 
ing as the vessels approached or receded, shows that 
the earth must have a curved surface, or in other 
words is a globe. 

To use your eyes in this way, and seek out the 
meaning of that which you see, would neither be a 
hard nor a dull task; and yet you would really be 
engaged in what is called observational science. 
When you watch how the ships at sea appear to you 
as they come and go, you observe facts. When 
you put the facts together, and reason out their 
connection and meaning, and find that they prove 
the earth to be a globe, you make an induction 
or inference from them. Now it is this union of 
observation and induction which makes science. 

24. We may observe, then, and prove, that the old 
and natural-enough notion about the flatness of the 
earth is quite untrue; and that, flat as the visible 
portions of the sea and land may appear, they are 
only parts of a great curve. If we were to set sail 
from England, and to travel on in the same general 
direction without turning back, we should in the 
end come to England again. We would sail round 
the world, and prove it to be actually a globe. Now, 


THE EARTH.] PHYSICAL GEOGRAPHY. 


13 


this has often been done. Many voyages have been 
made round the world, and, instead of coming to its 
edge, the voyagers or “circumnavigators,” as they 
are called, have always found the land and sea to 
wear the same curved surface which we can see for 
ourselves at home. 

25. Though it may be easy enough to believe that 



Fio. 2.—The Earth and Moon as they would appear seen from space. 


the surface of the earth is part of a curve when one 
looks out upon the broad sea, yet in a landscape 
where the ground is very uneven,—such, for example, 



14 


PHYSICAL GEOGRAPHY. 


[shape of 


as a region of high mountains and deep valleys,— 
there may perhaps he some difficulty in understand¬ 
ing how such an irregular surface can be spoken of as 
part of a curve. In reality, however, the earth is so 
big that even the highest mountains are in comparison 
merely like little grains on the surface. It is only 
when the surface is level, as on a great plain or on 
the sea, that we can usually judge by the eye as to 
the real form of the earth. But even in the most 
rugged ground the curve is there, though we may 
fail to notice it. 

26. But the curve, after all, is a very gentle one. 
You can follow the vessels at sea for many miles 
before they sink down out of sight. The fact that 
the curve is so gentle shows that the circle of which 
it forms part must be of great size. If a vessel 
could sail on a straight course round the earth, it 
would take many months to complete the voyage. 
Or if a railway train could go completely round the 
earth at a rate of thirty miles an hour without 
stoppage, it would take more than a month to make 
the circuit. 

27. Astronomers have been able to measure the 
earth, and have found that it is not a perfect sphere, 
but a spheroid,—that is to say, two opposite sides 
are depressed or flattened, so that the globe is shaped 
somewhat like an orange. A line drawn between 
the two flattened parts or poles measures rather 
more than 7899 miles. This is known as the polar 
diameter. A line from side to side through the 


THE EARTH.] PHYSICAL GEOGRAPHY. 15 

most bulging part or equator must be a little more 
than 7925 miles. This is termed the equatorial 
diameter. Hence the diameter of our earth is 
about 261 miles less between the poles than at the 
equator. You may find it difficult to form any 
proper notion in your minds of these distances. It 
is useful to walk for a mile or two between places 
the distance of which from each other you know, 
and then to try to realise how many thousand times 
you must multiply that distance to equal the diameter 
of our globe. 


DAY AND NIGHT. 

28. Day by day we have been accustomed all our 
lives to see Hie sun travel across the sky. Night 
after night, when the air has been free from cloud, 
we have seen the moon or stars sailing slowly over¬ 
head. We cannot be more confident of anything 
than that the sun will appear again to-morrow, and 
move on from j*ear to year as it has done in the 
past. A slow, regular, and unceasing motion seems 
to be going on all round the earth. Have you ever 
wondered what can be the cause of this motion ? 

29. When the sun shines it is warm, when clouds 
obscure the sky the air is more chilly, and at night 
we feel a sensation of cold. Again : by day the sky 
is filled with light, but when the sun sinks in the 
west darkness begins. Thus, we depend upon the 
sun for light and heat. It is evident that what 


16 


PHYSICAL GEOGRAPHY. 


[day and 


takes place upon the earth cannot be properly under¬ 
stood until something has been learnt about the 
relations of the earth to the sun. 

30. Our first impression in childhood is like that 
of mankind in general long ago. They believed the 
earth to remain as the fixed central point of the 
universe, round which sun, moon, and stars were 
ceaselessly revolving. To this day we speak of these 
heavenly bodies as rising and setting, as if we still 
regarded them as performing a journey round the 
earth. 

31. But it has now been known for several 
hundred years that instead of being the centre of 
the universe, our earth is in reality only one of a 
number of heavenly bodies that travel unceasingly 
round the sun, which is the great central hot mass 
that warms and lights them. That this must be 
true will appear if we attentively consider how day 
and night succeed each other. 

32. The alternation of day and night, apparently 
due to the movements of the sun, is in reality caused 
by the turning or rotation of the earth itself. This 
may be readily illustrated. A humming-top made to 
spin rapidly seems to stand for a while motionless 
upon its point, but it actually is rotating with great 
rapidity. Imagine a line passing straight up from 
the point below to the top of the stalk above. Every 
part of the top is spinning round this central line, 
which is called the axis of rotation. In a similar 
way the earth is spinning rapidly on its axis. 


NIGHT.] 


PHYSICAL GEOGRAPHY. 


17 


33. Another illustration may be made with an 
ordinary school-globe and a lighted candle placed a 
few feet from it, in a line with the brass circle. The 
globe can be made to turn round on its axis. Whether 
it is allowed to remain at rest or is sent spinning 
round rapidly, the half of it next the candle is 
lighted, and the other half away from the candle is 
in shade. When it is at rest, the places marked on 
one side remain in the light, while those on the 
opposite side remain in the dark. As it is turned 
round, each place in succession is brought round 
to the light, and carried on into the shade again. 
And while the candle remains unmoved, the rotation 
of the globe brings alternate light and darkness to 
each part of its surface. 

34. Instead of the little school-globe in this illus¬ 
tration, imagine our earth, and in place of the feeble 
candle, the great sun, and you will see how the rota¬ 
tion of the earth on its axis must bring alternate 
light and darkness to every country. 

35. No one will imagine that any actual rod passes 
through the earth, to form the axis round which it 
turns. The axis is only an imaginary line, and the 
two opposite points where it reaches the surface, and 
where the ends of the rod would come out, were the 
axis an actual visible thing, are called the North 
Pole and the South Pole. They are represented 
by the two little points by which the school-globe is 
fixed in its place. 

36. Round this axis the earth spins once in about 


18 PHYSICAL GEOGRAPHY. [day and 

every twenty-four hours. All this time the sun is 
shining steadily and fixedly in the sky. But only 
those parts of the earth can catch his light which 
happen at any moment to be looking towards him. 
There must always be a bright side and a dark side, 
just as there is a bright side and a dark side when 
you place a school-globe opposite to a candle. Were 
there no motion in the earth, then obviously half of 
its surface would never see the light at all, while the 
other half would never be in darkness. But since 
the earth rotates, every part is alternately illuminated 
and shaded. When we are catching the sun’s light, 
we have Day; when we are on the dark side, we 
have Night. 

37. The sun seems to move from east to west. 
The real movement of the earth is necessarily just 
the reverse of this, viz. from west to east. In the 
morning we are carried round into the sunlight, 
which appears in the east. Gradually the sun seems 
to climb the sky until we are brought directly opposite 
to him at noon, and gradually he sinks again in 
the west, as the earth in its constant rotation bears 
us round once more into the dark. Even at night, 
however, we can still trace the movement of the 
earth by the way in which the stars one by one rise 
and set, until their lesser lights are quenched in the 
returning light of another day. 

38. While the movement of rotation gives the 
succession of day and night, another movement of 
our globe measures out the length of the year. 


NIGHT.] 


PHYSICAL GEOGRAPHY. 


19 


Not only is the earth rotating on its axis, it is at 
the same time circling or revolving round the sun. 
This motion is called its revolution; and the path 
which the earth follows in its circuit round the 
sun is termed its orbit. We are ninety-two millions 
eight hundred thousand miles from the sun, so that 
to go completely round the sun, the earth has to 
travel over so wide a circuit or orbit that it takes 
rather more than three hundred and sixty-five days 
to perform the journey, even though it is rushing 
along at an average speed of about nineteen miles in 
a second. 

39. By the motion of rotation, time is divided 
into days and nights,—by that of revolution, it is 
marked off* into years. So that in this way the 
earth is our great time-keeper. There are other 
important results of the earth’s movements with 
which you will afterwards become acquainted. 

THE AIR. 

I. What the Air is made of. 

40. When we begin attentively to consider the 
world around us, one of the first things to claim 
notice is the air. We do not see it, and yet it is 
present wherever we may go. How profoundly it 
influences the life of man! How continually it 
changes its characters, and how much these altera¬ 
tions affect us !—now blowing in a gentle breeze, 
then sweeping along in a fierce storm, at one time 


20 


PHYSICAL GEOGRAPHY. 


[the air. 


cold, at another time warm, to-day clear and dry, 
to-morrow laden with vapour or drenched with rain. 
What, then, is this Air ? 

41. Although invisible, it is yet a real, material 
substance. Swinging your arm rapidly up and down 
you feel that the air offers a resistance to the hand. 
The air is something which one can feel, though one 
cannot see it. We breathe it every moment. We 
cannot get away from it, for it completely surrounds 
the earth as an envelope fifty miles or more in depth. 
Beyond the outer limits of the air, the region between 
us and the stars is called Space. To the envelope of 
air enclosing the earth the name of Atmosphere—that 
is, the region of vapours—has been given. 

42. The experiments explained in the Chemistry 
Primer (Art. 9) prove that air is a mixture of two in¬ 
visible gases, called nitrogen and oxygen. Besides 
these chief ingredients, it contains also small quan¬ 
tities of other substances—some of which are visible, 
others invisible. When the shutters of a room are 
closed, so as to let the sunlight stream through only 
one chink or hole into a room, you see some of the 
visible particles of the air. Hundreds of little motes 
or specks of dust cross the beam of light which, 
reflected from them as they float up and down, 
makes them visible against the surrounding darkness, 
though they disappear in full daylight. But it is 
the invisible parts of the air which are of chief 
importance; and among them, besides the two chief 
gases just mentioned, there are two which especially 


THE AIR. ] 


PHYSICAL GEOGRAPHY. 


21 


deserve to be remembered—the vapour of water 
and carbonic acid gas. 

43. Now what is this vapour of water 1 In watch¬ 
ing what takes place when a kettle boils you notice 
that from the mouth of the spout a stream of 
steam comes out into the air. It is in continual 
motion, rushing out of the spout, but at a short 
distance away it somehow disappears. All the 
time that this white cloud is coming and going the 
water in the kettle is growing less, until at last, if 
you do not replenish it, the whole will be boiled 
away, and the kettle be left quite dry. What has 
become of all the water ? It has been changed into 
steam. It is not destroyed or lost in any way: it 
has only passed from the condition of visible liquid 
in the kettle into that of an invisible vapour or 
gas in the air. Hut the substance is just as really 
present in the air, though unseen, as it was when it 
was poured into the kettle as water. 

44. The air always contains more or less vapour 
of water, which remains invisibly dissolved so long 
as it continues in the state of vapour. But, as will 
be explained a little farther on, this dissolved vapour 
is continually coming back again into visible water. 
It gives rise to clouds, mist, rain, and snow. If it 
were taken out of the air, everything would be dried 
up on the land, and life would be impossible. As you 
learn more and more of the changes that take place 
from day to day around you, you will come to see 
how large a part this vapour of water plays in them. 


22 


PHYSICAL GEOGRAPHY. 


[THE air. 


45. Carbonic acid gas is also one of the invisible 
gases of the atmosphere, of which it forms about four 
parts in every ten thousand. This may seem a very 
minute proportion, but it is enough to supply all the 
plants that grow upon the land with nearly the whole 
of their solid substance. Plants have the power of 
taking the carbon out of the air and building it up 
into their own framework (Chemistry Primer, Art. 11). 
When a plant dies and decays, carbonic acid gas is 
restored to the air again. On the other hand, plants 
are largely eaten by animals, and help to form the 
framework of their bodies. Animals in breathing 
give out carbonic acid gas into the air; and when 
they die the decay of their bodies returns the same sub¬ 
stance again to the soil and the atmosphere. Hence 
the carbonic acid gas of the air passes into the struc¬ 
ture of plants and then of animals, and is once more 
restored to the air when these living things die and 
their remains begin to decay. There is, in this way, 
a continual coming and going of this material be¬ 
tween the air and the animal and vegetable kingdoms 
(Chemistry Primer, Art. 13). 

II. The Warming and CooHng of the Air. 

46. Though we cannot see the air, we can feel it 
when it moves. A light breeze, or a strong gale, 
can be just as little seen by the eye as still air; and 
yet we readily feel their motion. But even when 
the air is still, it can make itself sensible in another 
way, viz, by its temperature (Physics Primer, Art. 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


23 


51). For air, like common visible things, can be 
warmed and cooled. 

47. This warming and cooling of the air is familiar 
to us in dwelling-houses. If you pass out of a warm 
room on a winter’s day into the open air, you feel 
cold. Whence does this sensation come 1 Not from 
anything you can see, for your feet, though resting 
on the frozen ground, are protected by leather, and 
do not yet feel the cold. It is the cold air encircling 
you on all sides that robs you of your heat; while at 
the same time you are giving off or radiating heat 
from your skin into the air (Physics Primer, Art. 
67). On the other hand, if, after standing a while 
in the chilly winter air, you return into the room 
again, you feel warm. Here, again, the feeling does 
not come from any visible object, but from the invis¬ 
ible air which touches your skin, and is thus robbed 
of its heat by you. 

48. Air, then, may vary greatly in temperature,— 
that is, it may sometimes be warm and sometimes 
cold, and yet still remain quite invisible. By means 
of the thermometer (which is explained in the Physics 
Primer, Art. 51), we can measure slight changes of 
temperature, which even the most sensitive skin 
would fail to detect. 

49. Now, how is it that the atmosphere should 
sometimes be warm and sometimes cold 1 Where 
does the heat come from ? and how does the air 
acquire it 1 

50. Let us return again to the illustration of the 


24 


PHYSICAL GEOGRAPHY. 


[the air. 


house. In winter, when the air is keen and frosty 
outside, it is warm and pleasant indoors, because 
fires are there kept burning. The burning of coal 
and wood produces heat, and the heat thus given 
out warms the air. Hence it is by the giving off or 
radiation of the heat from some burning substance 
that the air of our houses is made warmer than the 
air outside. 

51. Now, it is really by radiation from a heated 
body that the air outside gets its heat. In sum¬ 
mer the air outside is sometimes far hotter than is 
usual in dwelling-houses in winter. All this warmth 
comes from the sun, which is an enormous hot mass, 
continually sending out heat in all directions. 

52. But if the sun is always pouring down heat 
upon the earth, why is the air ever cold 1 Place a 
screen between you and a bright fire, and you will 
immediately feel that some of the heat from the fire¬ 
place has been cut off. When the sun is shining 
expose your hand to its beams for a time, and then 
hold a book between the hand and the sun. At first 
your skin is warmed; but the moment you put it in 
the shade it is cooled again. The book has cut off 
the heat which was passing directly from the sun to 
your hand. When the atmosphere is felt to be cold, 
something has come in the way to keep the sun’s 
heat from directly reaching us. 

53. Clouds cutoff the direct heat of the sun. We 
have all often noticed the change of temperature 
when, after the sun has been shining for a time, a 


THE AIH.] 


PHYSICAL GEOGRAPHY. 


25 


cloud comes between it and tlie earth. Immediately 
a feeling of chilliness is experienced, which passes off 
as soon as the cloud has sailed on and allowed the 
sun once more to come out. 

54. The air itself absorbs some of the sun’s heat, 
and the greater the thickness of air through which 
that heat has to make its way, the more heat will be 


B 



Fig. 3.—Diagram showing the influence of the varying thickness of the 
Atmosphere in retarding the Sun’s heat. a. Line of Sun’s rays in the 
morning, b. Line of the rays at noon. c. Line of the rays at sunset. 

absorbed. Besides this, the more the rays of heat 
are slanted the weaker do they become. At noon, 
for example, the sun stands high in the sky. Its rays 
(as at b in Fig. 3) are then nearest to the vertical, and 
have also the least thickness of air to pass through 
before they reach us. As it descends in the after¬ 
noon, its rays get more and more slanted, and must 
also make their way through a constantly increasing 
thickness of air (as at C in the diagram). Hence the 
middle of the day is much warmer than morning or 
evening. 

55. At night, when the sun no longer shines, its 
heat does not directly warm the part of the earth in 

fi 







26 


PHYSICAL GEOGRAPHY. 


[the air. 


shadow. That part not only receives no heat from 
it, hut even radiates its heat out into the cold sky 
(see Art. 59). Hence night is much colder than day. 

56. Then, again, during summer the sun at noon 
shines higher in the sky, or more directly overhead, 
than in winter. Its heat comes down less obliquely, 
and has less depth of air to pass through, and hence 
is more felt than-in winter, when the sun in northern 
parts of the world never rises high even at midday. 

57. From all this it is evident that we get our 
supplies of heat from the sun, and that anything 
coming between us and the sun serves to interrupt 
this heat and give us the sensation of cold. 

58. Still, if we were dependent for our warmth 
upon the direct heat of the sun alone, we should be 
warm only when the sun shines. A cloudy day would 
he an extremely cold one, and every night as intensely 
frosty as it ever is in winter. Yet such is not the 
case. Cloudy days are often quite warm; while the 
nights are by no means always very cold. There 
must be some way in which the sun’s heat is stored 
up, so that it can he felt even when he is not shining. 

59. Let us again have recourse to our first illus¬ 
tration. The back of a chair placed opposite to a 
bright fire gets so hot that you can hardly touch it. 
Remove the chair to a distant part of the room, and 
it quickly cools. Heat radiated from the fire has been 
absorbed by the wood, and again given out. 

60. In like manner, in summer the ground is 
warmed; in some parts, indeed, it becomes so hot at 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


27 


times that one can hardly keep the hand upon it. 
Soil and stones absorb and radiate heat readily,— 
that is to say, soon get heated, and soon cool again. 
When they have been warmed by the sun, the air 
gets warm by contact with them, and keeps its heat 
longer than they do; so that even when at night 
the soil and stones have become ice-cold, the air a 
little above them is not so chilly. On the other 
hand, when the surface of the ground is cold, it cools 
the air next it. As the ground parts easily with its 
heat, a vast amount of heat is in this way radiated 
at night from the earth outward into cold starry space. 

61. Much more heat, however, would be lost from 
this cause, did not the abundant invisible aqueous 
vapour of the atmosphere (Art. 43) absorb part of it, 
and act as a kind of screen to retard the radiation. 
If all the vapour were taken out of the air, the 
night, owing to the rapidity with which the earth 
would radiate its heat into space beyond, would be 
intensely cold. This is the reason why in hot desert 
climates, where the air is very dry—that is, contains 
a comparatively small proportion of the vapour of 
water—the nights are relatively colder than they 
are in cooler climates where the air is moister, while 
the days are often intolerably hot. Both the invisible 
vapour of water dissolved in the air, and the same 
substance when condensed into visible clouds, serve 
to keep heat from escaping. Hence cloudy days need 
not be cold, while cloudy nights are usually not so 
cold as those which are clear and starry. 


28 


PHYSICAL GEOGRAPHY. 


[the air. 


62. The atmosphere, then, is heated or cooled ac¬ 
cording as it lies upon a warm or cold part of the 
earth’s surface; and, by means of its aqueous vapour, 
it serves to store up and distribute this heat, keeping 
the earth from such extremes of climate as would 
otherwise prevail. 

III. The Vapour in the Air. Evaporation 
and Condensation. 

63. The presence of water-vapour in the air not 
only keeps the earth from losing its heat so fast at 
night, and screens it from the great heat and glare of 
the sun during the day, but leads to many other con¬ 
sequences, some of which we must try to understand. 
First of all, we may inquire how tho vapour gets into 
and out of the air. In this case, as before, we find 
that great questions in science often admit of being 
simply and readily illustrated by the most familiar 
things. 

64. In a warm room, where a good fire has been 
burning all day, and a number of people have been 
gathered together, the air might be thought to be 
tolerably dry. But bring a tumbler of ice-cold water 
into the room, and mark what happens. You will 
see the outside of the glass immediately covered with 
a fine film of mist. In a little while minute drops 
of water will form out of this film, and will go on 
growing, until, perhaps, some of them unite and trickle 
down the side of the tumbler. 

65. You may have noticed, too, that on very cold 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


29 


nights, the windows of sitting-rooms or crowded public 
halls are found streaming with water on the inside. 

66. Now, in such cases, where does the moisture 
come from ? Certainly not out of the glass. It is 
derived from the water-vapour present in the air. 
This word vapour is often used to describe some kind 
of visible mist or fog or cloud. But these visible 
forms of moisture are not properly vapour in the 
sense in which the term is used in science. The 
water-vapour of the air is always invisible, even when 
the air is saturated with it—that is to say, when it 
cannot retain any more dissolved vapour. Only when 
the vapour passes back into the state of water is any¬ 
thing actually to be seen. 

67. When the invisible vapour dissolved in the 
air becomes visible, as in mists, clouds, dew, or rain, 
it is said to be condensed, and this process of the 
conversion of an invisible gas into a visible liquid is 
called condensation. 

68. The quantity of vapour which the air can con¬ 
tain varies according to temperature, warm air being 
able to hold more than cold air. This may be proved 
in a simple way. In breathing we exhale at each 
breath a quantity of water-vapour; when the air is 
warm, this invisible vapour, as soon as it escapes from 
us, mixes with the outer air, and is kept dissolved 
there. But if we cool the breath as it leaves our 
mouths, the vapour is at once condensed into visible 
moisture. Take a mirror, for example, or any other 
cold surface, and breathe on it: the vapour from your 


30 


PHYSICAL GEOGRAPHY. 


[the air. 


lungs at once shows itself in a film of mist upon the 
glass, because the air in contact with the cold surface 
is chilled and cannot hold so much vapour, part of 
which is condensed. During winter a mirror is not 
required to make the vapour of the breath visible, 
for the surrounding cold air at once condenses this 
vapour as it comes from the mouth, and forms the 
fine cloud or mist which appears with each breath 
that is exhaled. 

69. As the air is cooled, its power of retaining 
vapour diminishes. When it becomes colder than the 
temperature at which it is able to keep its supply of 
vapour dissolved, the excess of vapour is condensed 
and becomes visible. The temperature at which this 
takes place is the point of saturation, or Dew-point 
(see Arts. 77, 78). 

70. Now let us inquire how it is that the vapour, 
so universally present, gets into the atmosphere, and 
where it comes from. Pour a little water into a 
plate, or, still better, on a black tray, marking pre¬ 
cisely the line of the edge of the water, and set it 
down in the open air. In the course of perhaps an 
hour or two, unless in very damp weather, the water 
may be observed to have sensibly diminished. The air 
has drunk up part of it, and will drink up the whole, 
if the water is allowed to stand long enough. What 
takes place from this small quantity of water goes on 
from every surface of water on the face of the earth, 
from every brook and river and lake, and from the 
great sea itself. Water is constantly passing off into 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


31 


vapour, which is received and retained by the air. 
This process is called Evaporation, and the water 
which passes off into vapour is said to be evaporated. 

71. Since warm air can hold more vapour than 
cold air, evaporation must be more vigorous in sun¬ 
shine than at night, and during summer than during 
winter. The sun is the great source of heat that 
keeps evaporation so active. We are all doubtless 
familiar with the great difference in the rate at which 
wet roads dry up. When the sun shines warmly, 
an hour or two may be enough to drive off the 
moisture from them, and make them white and hard 
again. But if the weather is cold and dull, they may 
remain wet and damp for many days. In the one 
case, the warm air greedily absorbs vapour from the 
water on the roads; in the other, the cool air takes 
it up only in small quantities. 

7 2. Again, it is plain that in damp weather there 
must be less evaporation than in dry weather. On 
a dry breezy day, evaporation goes on rapidly, because 
the air has not nearly all the quantity of vapour it 
can hold in solution. But on a damp day, when the 
air contains about as much vapour as it can hold 
at that particular temperature, evaporation is quite 
feeble, or ceases altogether. This varying capacity 
of the air for vapour is the reason why laundresses 
find such a contrast in the ease with which they can 
have their clothes dried on different days. Some¬ 
times the air is busy drinking up vapour everywhere, 
or, as we say, there is great drought, and then the 


32 


PHYSICAL GEOGRAPHY. 


[THE air. 


clothes dry quickly. Such is especially the case when 
the sky is clear and there is a little wind, because 
every moment a fresh quantity of air comes in con¬ 
tact with the clothes, carries off some of the vapour, 
and passes on to make way for fresh supplies of 
thirsty air. At other times, when the air can hardly 
hold any more vapour, the clothes are found at the 
end of the day to be almost as wet as when they 
were hung out in the morning. 

73. When water evaporates, the vapour carries 
away heat with it. Put a drop of water on the back 
of your hand, and let it evaporate ; you feel the part 
cold, because the vapour as it passes from the drop 
into the air has robbed your skin of some of its heat. 
This absorbed heat is given out again into the air 
when vapour is condensed. 

7 4. The invisible water-vapour in the air, though 
very small in quantity when compared with the 
amount of nitrogen and oxygen, is yet enormous 
when the whole mass of the atmosphere is considered. 
It has been calculated that the amount of vapour 
that rises every year from the earth’s surface into the 
air would, if condensed, cover with water a country 
nearly as large as France to the depth of one mile. 
This vapour is raised in gaseous form from every 
water-surface over the whole earth by the process of 
evaporation, and is brought back again into liquid 
form by the process of condensation. 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


33 


IV. Dew, Mist, Clouds. 

75. After sunset, when the sky is clear, the grass 
becomes wet with dew. In the morning a white 
mist or fog may often be noticed hanging over woods, 
streams, and hills, but gradually melting away as the 
sun mounts in the sky. At all times of the year clouds 
may be seen to form and dissolve, and form again, 
ever changing their size and shape as they move 
through the air. Now these are all examples of 
the condensation of vapour. Let us watch how 
the process takes place. 

76. Condensation, as we have seen (Art. 68), arises 
from a cooling of the air. When vapour is condensed, 
it does not at once take the form of running water. 
The cold glass brought into the warm room has first 
a fine film of mist formed upon it, and then by 
degrees the clear drops of water come (Art. 64). 
In reality, mist is made up of exceedingly minute 
particles of water, and it is the running together of 
these which makes the larger drops. So in nature 
on the great scale, when condensation occurs, the 
vapour first appears as a fine mist. In looking at a 
mist or cloud as it forms, either in the sky or near 
the ground, we may be quite certain that air, in 
which water-vapour is dissolved, is from some cause 
being cooled down till it cannot hold all its vapour 
any longer, and must part with some of it. 

77. Dew.— This name is given to the wetness 
which appears in the evening or at night upon grass, 


34 


PHYSICAL GEOGRAPHY. 


[the air. 


leaves, stones, or other surfaces freely exposed to the 
sky. ‘In the morning, after a dewy night, the little 
dewdrops sparkle upon the foliage and upon the 
delicate threads of gossamer. Now this wetness does 
not come out of the grass, leaves, or stones. It is 
all derived from the air by condensation, exactly as 
the film of mist forms upon a cold tumbler in the 
warm moist air of a room. In fact, such a film of 
mist is really dew, all dew being formed from the 
same cause. 

78. At night, when the sky is clear, the earth radi¬ 
ates heat rapidly; in other words, it gives off into 
cold space much of the heat which it has received 
from the sun during the day (Art. 60). Its surface 
consequently becomes cold, as may be felt by putting 
the hand upon leaves or stones after nightfall. The 
layer of air next the cooled ground is chilled below 
its point of saturation—that is, it is reduced to a 
temperature at w r hich it can no longer hold so much 
dissolved vapour. The excess of vapour is deposited 
as dew upon grass, twigs, stones, and other objects. 
The temperature at which this condensation begins 
to take place is called the Dew-point (Art. 69). 

7 9. Mist and Fog.—Another way in which a cold 
surface of the earth may produce condensation is 
shown by what takes place among mountains. When 
a warm moist wind blows over a chill mountain top, 
it is cooled, and its vapour becomes visible in the 
form of a mist or cloud. The cloud may be quite 
solitary, and may even shape itself to the form of the 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


35 


ground, as if it were a sort of fleecy cap drawn down 
over the mountain’s head. This is often well marked 
in the morning. As day advances, the ground, 
warmed by the sun, no longer cools the air, and hence 
the mist is gradually re-absorbed into the atmosphere. 
But by-and-by, at the coming on of night, when the 
ground is once more cooled by radiation, if there 
should be vapour enough in the air, the mist will re¬ 
form, and the mountain will put on his cap again. 

80. Cold air, as well as cold ground, condenses the 
vapour of warmer air. Watching what goes on along 
the course of a river, you will often see examples of 
this kind of condensation. The ground on either 
side of the river parts with its heat after sundown 
sooner than the river itself does, and consequently 
cools the air above it more than the air above the 
river is cooled. So when this colder air from either 
side creeps down to take the place of the warmer 
damp air lying on and rising from the river, con¬ 
densation ensues in the form of the mist or river- 
fog, which so commonly hangs at night and early 
morning over streams. 

81. Clouds.—It is not on the ground, however, 
but up in the air, that the chief condensation of 
vapour takes place. No feature of everyday occur¬ 
rence is more familiar than the clouds, which are the 
result of this condensation. A cloud is merely a 
mist formed by the cooling of warm moist air which 
loses its heat from any cause, such as expansion 
during ascent, or contact with currents of cooler air. 


36 


PHYSICAL GEOGRAPHY. 


[the air. 


Watching what goes on in the sky, we may often 
see clouds in the act of forming. At first a little 
flake of white appears. By degrees this grows larger, 
and other cloudlets arise and flock together, until at 
last the sky is quite overcast with heavy clouds, and 
perhaps, in the end, rain begins to fall. The vapour, 
thus condensed in the air, has all been obtained by 
the evaporation of water on the earth’s surface. It 
rises with the warm air, which, losing heat as it as¬ 
cends, and also coming in contact with colder layers 
of the atmosphere, cannot hold all its vapour, and 
the excess, of which it must get rid, is then con¬ 
densed into cloud. 

82. On a summer morning the sky may be free 
from cloud ; but as the day advances, more 
vapour is raised from the warmed earth, which, 
borne upward by the warm ascending air-currents 
into higher and colder parts of the atmosphere, is 
there chilled into the white fleecy clouds that form 
about midday and in the afternoon. Towards even¬ 
ing, when the warm ascending currents die away, 
and less evaporation takes place, the clouds cease 
to grow. They then begin to sink in the sky and 
gradually lessen in size, until at night the heavens 
may be quite clear again. They have been once more 
dissolved by descending and coming in contact with 
warm air nearer to the earth. Again, clouds move 
across the sky, driven along by upper currents of air. 
The stronger these currents, the faster do the clouds 
travel. In this way the sky is sometimes completely 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


37 


overcast with clouds which have come from a dis¬ 
tance. By watching these comings and goings of the 
clouds, we see how continually the state of the vapour 
in the atmosphere changes—how at one time it is 
condensed into clouds, at another time evaporated 
and invisibly dissolved in the air. The movements 
of the air are, indeed, in great measure dependent 
upon the variations and amount of water-vapour 
(Art. 98). 

V. Rain and Snow. 

83. The vapour which the sun’s heat raises from 
rivers, lakes, and seas is condensed again into visible 
form as clouds. But the clouds do not remain 
always suspended in the sky. They disappear in 
two different ways. Sometimes, as already noted 
(Art. 82 ), they are anew dissolved into invisible 
vapour. At other times they let their moisture fall 
through the air to the earth, and thus give rise to 
rain and snow. 

84. Rain.—No fact in nature is more familiar 
than that rain comes from clouds in the sky. When 
the sky is clear overhead, rain hardly ever falls, but 
when it becomes overcast, rain often appears. We 
may watch a dark rain-cloud gather itself together 
and discharge a heavy shower upon the earth, the 
long dark streaks of rain being seen actually passing 
from the cloud above to the ground below. In the 
illustration of the cold glass brought into the warm 
room (Art. 64), the film of mist formed upon the 


38 


PHYSICAL GEOGRAPHY. 


[the air. 


glass is found by degrees to gather into drops, which 
trickle down the cold surface. Now the mist on the 
glass and the cloud in the sky are both formed of 
minute particles or drops of water. It is the running 
together of these exceedingly small particles which 
give rise to the rain-drops. In the one case, the 
water trickles down the cold glass. In the other 
case, it gathers into drops of rain that fall through 
the air. The minute particles of the cloud, as con¬ 
densation proceeds, grow bigger until they form drops 
of water too heavy to hang any longer suspended in 
the air. These then fall to the earth as rain-drops. 

85. Snow.—But there is another important form 
in which the moisture of the clouds may descend to 
the surface of the earth. In those countries where 
the weather is cold enough, there fall to the ground 
not drops of rain, but flakes of snow. 

86. A handful of snow brought indoors soon melts 
into water, which, on further exposure to the air, 
evaporates. Snow, water, and water-vapour are thus 
only different forms of the same substance. The 
material which we call water can thus exist in three 
forms,—the gaseous, the liquid, and the solid. Snow 
is an example of the solid condition. 

87. On a frosty night pools of water are covered 
with a hard transparent crust of what is called Ice. 
You may break this crust into pieces, but if the cold 
continues, a new crust will soon be formed with bits 
of the old one firmly cemented in it. And the greater 
the cold the thicker will the crust be, until perhaps 


THE AIR.] PHYSICAL GEOGRAPHY. 59 

the whole of the water in the pools may become solid. 
A piece of this solid substance is found on examination 
to be cold, brittle, and transparent. Brought into a 
warm room it soon melts into water, which may easily 
be driven off, as before, into vapour. Ice is the general 
name given to water when it is in the solid state, 
such forms as snow and hail being only forms of 
ice. Whenever water becomes colder than a certain 
temperature it passes into ice, or freezes, and this 
temperature is consequently known as the freezing- 
point (Physics Primer, Art. 51). 

88. Ice, as we usually see it, might be supposed to 
be a shapeless thing. But gather a few snowflakes, 
and, that they may not melt, examine them out of 



Fig. 4.—Forms of Snowflakes. 


doors. When they lie together in a mass they have 
a pure opaque whiteness, but in reality they are as 
transparent as water; and it is only from the way 
in which they scatter the light from their many glis¬ 
tening points that they appear white. To be assured 
of this fact, carefully separate one or two of the flakes 
upon some dark surface (the sleeve of a coat will do 
well), and you will find that each flake is a more or 
less perfect star with six rays, formed of little needles 
or crystals of pure transparent ice. The flakes are so 



40 


PHYSICAL GEOGRAPHY. 


[the air. 


delicate that in falling through the air they are apt to 
be damaged by coming against each other. Some of 
their varieties are shown in Fig. 4. 

89. In proportion as we rise above the surface of 
the earth, the temperature falls. This is observed 
on any high mountain, and also in balloon-ascents. 
The upper layers of the atmosphere are much 
colder than the freezing-point of water. Any vapour, 
therefore, which is borne aloft by the upstreaming 
currents of warm air from the earth’s surface is frozen 
in these high regions, and passes into crystals of ice 
or snow. The fine white cloudlets which may be 
seen floating at great heights are probably formed of 
snow. But in countries, such as the northern parts 
of Europe and North America, where in winter the 
air even at the surface is sometimes very cold, snow 
falls to the ground and lies there as a white covering, 
until returning warmth melts it away. 

90. Besides rain and snow, the moisture of the air 
takes sometimes the form of Hail, which consists of 
little lumps of ice like frozen rain, and of Sleet, 
which is partially-melted snow. But rain and snow 
are the most important, and we will follow them a 
little farther, to learn what part they take in the 
changes that affect the surface of the land. (See 
Arts. 104, 187.) 

VI. The Movements of the Air. 

91. A very little attention suffices to show that 
the air is never at rest. For the most part we can 


THE AIR.] PHYSICAL GEOGRAPHY. 41 

feel its movements, from the gentlest breeze up to 
a high gale. And even when it is so still that 
we are not sensible of any motion in it at all, we 
have only to watch the leaves on the trees, or the 
smoke ascending from chimneys, to see that at least 
slight puffs of air must arise, for the leaves now 
and then quiver, and the smoke seldom goes up 
quite straight, but turns as it is borne away to one 
side or the other. Let us consider how the air is 
set in motion. 

92. The air lying next to a hot surface is heated; 
the air touching a cold surface is cooled. Hot or 
warm air is lighter than cold air. Heat expands 
bodies (Physics Primer, Art. 49), and this expan¬ 
sion of air, or the separation of its particles farther 
from each other, makes it less dense or heavy 
than cold air, where the particles lie more closely 
together. As a consequence of this difference of 
weight or density, the light warm air rises, and the 
heavy cold air sinks. This statement may be readily 
tested by experiment. Take a poker, and heat the 
end of it in the fire until it is red-hot. Withdraw 
it, and gently bring some small bits of very light 
paper, fine down, or some other light substance a few 
inches above the heated surface. The bits of paper 
or fibres of down are carried up into the air. This 
happens because the air heated by the poker imme¬ 
diately rises, and its place is taken by colder air, 
which, on getting warmed, likewise ascends. Hold¬ 
ing the hot end of the poker between our eyes and 


42 


PHYSICAL GEOGRAPHY. 


[the air. 


the light, we may actually see the tremour of the 
upstreaming air, by the way in which it distorts the 
outlines of objects beyond. 

93. Fireplaces are constructed on the principle 
that heated air ascends. The fire is not kindled on 
the hearth, for, in that case, it would not get a large 
enough draught of air underneath, and would be apt 
to go out. It is placed a little above the floor, and 
a chimney is put over it. As soon as the fire is 
lighted, the air next it, being warmed, begins to 
mount, and the air in the room is drawn in from 
below to take the place of that which rises. All the 
air that lies above the burning coal becomes warmer 
and lighter; it therefore flows up the chimney, carry¬ 
ing with it the smoke and gases. Though a bright 
blazing fire is a pleasant sight in winter, only a 
part of its heat goes to warm the room. A great 
deal of the heat goes up the chimney; and, except 
in so far as it warms the walls, passes away and 
warms the outer air. But an open fireplace lias the 
advantage of causing a constant draught of air from 
outside into the room, to supply the place of the 
warmed air that passes out by the chimney. It thus 
promotes ventilation. A close stove, on the other 
hand, in which the indraught of air into the burning 
coal or wood is made comparatively small, and in 
which a large warm surface of metal or earthenware 
thoroughly warms a room, does not help ventilation, 
which must be otherwise provided for, to keep the air 
from soon becoming close and unhealthy. 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


43 


94. What happens in a small way in houses takes 
place on a far grander scale in nature. As already 
pointed out, the sun is the great source of heat which 
warms and lightens our globe. While the heat of 
the sun is passing through the air, it does very little 
in the way of warming it; but it warms the surface 
of the earth. In summer, the direct rays of the sun 
may be hot enough to burn one’s face, and yet even 
a thin sheet of paper, placed between the face and 
the sun, at once arrests the sensation of burning heat, 
although the same air is playing about the face all 
the time. 

95. Both land and water are heated by the sun’s 
rays, and the same kind of movement of the air takes 
place as can be watched by the fireside. The layer 
of air next the warmed earth becomes itself warmed. 
As it thereby grows lighter it ascends, and its place 
is taken by colder air, which flows in from the neigh¬ 
bourhood to take its place. This flowing in of air 
is Wind. 

96. It is easy now and then to watch how wind 
arises. Suppose, for instance, that during the summer 
we visit the sea-coast. In the morning and early 
part of the day a gentle wind will often be noticed, 
blowing from the sea to the land. As the day 
advances and the heat increases, this wind dies 
away. But after a while, when the day is beginning 
to sink towards evening, another breeze may be 
noticed springing up from the opposite quarter, and 
blowing with a delicious coolness from the land to 


44 PHYSICAL GEOGRAPHY. [the air. 

the sea. These breezes are the result of the unequal 
heating and cooling of sea and land. 

97. Let us understand how this takes place. On 
a hot day, stones, soil, or other parts of the land 
become very warm under the sun’s rays; yet if one 
bathes in the sea at that time, one feels its waters to 
be pleasantly cool. This shows that the land becomes 
more quickly hot than the sea. On the other hand, 
after such a hot day the surface of the land becomes 
at night much colder than the sea. It parts with its 
heat sooner than the sea does. By day, the hot land 
heats the air above it, and makes it lighter, so that 
it ascends; while the cooler and heavier air lying on 
the sea flows landward as a cool and refreshing sea- 
breeze. By night, this state of things is just re¬ 
versed ; for then the air which lies on the chilled 
land, being colder and heavier than that which covers 
the warmer sea, flows seaward as a cool land-breeze. 

98. It is clear, then, that one main cause of the 
movements of the air must be differences of temper¬ 
ature. But another highly important cause of these 
movements is to be found in the constant changes in 
the quantity of water-vapour present in the air. This 
vapour being lighter than air, a mixture of vapour 
and air is lighter than the same quantity of air; and 
of course the more the amount of vapour increases, 
the less dense does the mixture become. The weight 
or pressure of the atmosphere is measured by the 
familiar instrument called the Barometer. The 
greater the pressure the farther the barometer rises, 


THE AIR.] 


PHYSICAL GEOGRAPHY. 


45 


and the lower the pressure the more it falls. The 
effect of the ascent of much water-vapour into the 
air is to lessen the pressure and make the barometer 
fall. A low barometer, as it is called, generally 
accompanies wet and stormy weather. 

99. Any change in the weight or pressure of the 
atmosphere, caused by the addition of more water- 
vapour, must give rise to movements of the air. The 
lighter mixture of warm air and vapour ascends, and 
heavier, cooler, and drier air flows in from all sides 
to supply the place of the upward current. Hence 
arise winds and storms. 

100. When, from alteration of temperature or from 
variation in the amount of water-vapour, the weight 
of the air over one region is rapidly made less than 
over other surrounding districts, the air from these 
places flows violently into the central region, and the 
greater the difference between the pressure of the 
atmosphere in two neighbouring areas, the more 
furious will the inrush of air be. It is to this cause 
that hurricanes are due. 

101. There are certain regions of the earth’s surface 
where the pressure of the air is always high, and 
others where it is always low; consequently there is 
a continual interchange of air between these regions. 
The wind blows from the high-pressure tracts into 
those of low pressure. The chief region of low 
pressure encircles the globe as a great belt round the 
equator, and for some distance on either side. The 
air is there warm and moist, and evaporation is rapid. 


46 


PHYSICAL GEOGRAPHY. [circulation 


Consequently there is a constant upstreaming of warm 
moist air, which, as it rises farther from the earth’s 
surface, condenses into copious rains. But the ascent 
of this equatorial hot air requires the instreaming of 
cooler air from regions of higher pressure lying to the 
north and south. This constant flowing of air into the 
equatorial regions forms what are known as the Trade 
Winds. The steadiness of these winds, and the way 
in which they may be counted upon in navigation, led 
long ago to their being called by their present name. 

102. But whether gentle and constant, or fitful 
and violent, the cause of wind is always to be sought 
in differences between the weight or pressure of the 
atmosphere in adjacent districts, the rule being that 
wind always blows from where the pressure is high 
to where it is low. 


THE CIRCULATION OF WATER ON THE 
LAND. 

103. In the foregoing pages we have found that 
from every sheet of water on the face of the globe 
the air receives vapour; that this vapour is condensed 
into visible form, appearing as dew, mist, and cloud; 
that the vapour of which clouds are formed is resolved 
into rain, snow, hail, or sleet, and, in one or other of 
these forms, descends to the earth again. There is 
thus a circulation of water between the solid earth 
beneath and the air above. This circulation is a 3 


OF WATER.] PHYSICAL GEOGRAPHY. 


47 


essential to the earth, in making it a fit habitation for 
living things, as the circulation of blood is in keeping 
our bodies alive. It mixes and washes the air, clear¬ 
ing away impurities, such as those which rise from 
the chimneys of a town. It moistens and quickens 
the soil, which it renders capable of supporting vege¬ 
tation. It supplies springs, brooks, and rivers. In 
short, it is the very mainspring of all the life of the 
globe. So important a part of the machinery of the 
world deserves our careful consideration. Let us 
next attend, therefore, to what becomes of rain and 
snow after they have been discharged from the air 
upon the surface of the earth. 

I. What becomes of Rain. 

104. Although water is continually being evapor¬ 
ated from the surface of the earth, and continually 
restored to it again by condensation, yet, on the 
whole and in the course of years, there seems to be 
no sensible gain or loss of water in our seas, lakes, 
and rivers; so that the two processes of evaporation 
and condensation balance each other. 

105. It is evident, however, that the moisture 
precipitated at any moment from the air is not at 
once evaporated again. When a shower of rain falls, 
the roads are not dry the moment the shower is over. 
And when heavy rain continues for many hours to¬ 
gether, the whole country round may be flooded, and 
may remain so for days after the rain has ceased. 
The disappearance of the water is due in part to 


48 


PHYSICAL GEOGRAPHY. [circulation 


evaporation, but only in part. A great deal of it 
goes out of sight in other ways. 

106. As the surface of the sea is about three times 
greater than that of the land, the quantity of rain 
that falls upon it is probably the largest part of the 
whole rainfall of the globe. Mingling with the water 
of the sea, it helps to make up for the loss which the 
sea is always suffering by evaporation. For the sea 
is the great evaporating surface whence most of the 
vapour of the atmosphere is derived. 

107. The total amount of rain that falls upon all 
the land of the globe must nevertheless be enormous. 
It has been estimated, for example, that about 68 
cubic miles of water annually descend as rain even 
upon the surface of the British Isles, which is not 
one of the wettest parts of the globe. In some parts 
of India there is so much rain in the year that if it 
were to remain where it falls it would cover the 
ground to a depth of 41 feet. 

108. But rain does not lie where it falls. It soon 
disappears, and in a way that deserves close atten¬ 
tion. Watch what happens during a shower of rain. 
If the shower is heavy, little runnels of muddy water 
course down the streets or roads, and flow out of the 
ridges of the fields. Follow one of these runnels. 
It leads into some drain or brook—the brook into 
some larger stream—the stream into a river; and 
the river, if you follow it far enough, will bring you 
to the sea. The rain, therefore, in part at least, flows 
off the land into the sea. When we consider the great 


OF WATER.] PHYSICAL GEOGRAPHY. 


49 


number of brooks and rivers in the world, where this 
kind of transport of water is going on, we see how 
vast must be the amount of rain-water carried into 
the sea. 

109. But a very little reflection will convince you 
that only a part of the rain flows off by brooks and 
rivers. Since from every water-surface vapour rises 
into the atmosphere, part of the rain which reaches 
the ground is, no doubt, at once evaporated, and this 
evaporation must continue as long as the water re¬ 
mains exposed to the air. Experiments and measure¬ 
ments have been made to ascertain what proportion 
of the rainfall is lost by evaporation, and it has been 
inferred that this proportion amounts to from three- 
fourths to two-thirds; in other words, only about a 
third or fourth part of the total rainfall is discharged 
into the sea by rivers. 

110. Further observation, however, will lead you 
to perceive that there is yet another direction in 
which the rain goes out of sight. Suppose that after 
the soil has been baked by a long drought, heavy 
rain should come, and that you then dig up a spade¬ 
ful of earth. Do you find the ground dry now ? 
No; because some of the rain has soaked into the 
earth. And if you could dig deep enough, or would 
notice what goes on when workmen are making a deep 
excavation, you would find that the ground under¬ 
neath the soil is not merely damp, but that it contains 
plenty of water, and that this water can be collected 
and brought up to the surface. Clearly, then, a good 


50 


PHYSICAL GEOGRAPHY. [circulation 


deal of the rain which falls upon the land must sink 
underground and gather there. When it disappears 
in this way, is it finally withdrawn from the general 
circulation which we have been tracing 1 or if not, 
how can it ever get up to the surface again 1 

111. Consider the matter for a little, and you will 
be convinced that, whatever becomes of it, the water 
that descends below the soil cannot be lost to the 
general circulation. If it were for ever removed from 
the surface, the quantity of water upon the earth 
would be constantly and visibly diminishing. The seas 
would get narrower and shallower; the rivers and 
lakes would dry up. But no such changes, so far as 
can be seen, are really taking place. The sea rolls as 
broadly and deeply as it has done for many genera¬ 
tions past; the lakes and rivers remain very much 
the same. So that if any of the water that sinks 
into the earth is never restored to the surface again, 
it must be so small a part as to make no sensible 
difference on the amount which is restored. In spite 
of the rain that disappears into the ground, the cir¬ 
culation of water between the air, the land, and the 
sea, continues without perceptible diminution. 

112. Obviously, therefore, there must be some 
means whereby the water underground is brought 
back to the surface. This is done, as you will learn 
in the next section, by Springs, which gush out of 
the earth, and bring up water to feed the Brooks 
and Rivers, whereby it is borne into the sea. 

113. You can now answer the question, What be- 


OF WATER.] PHYSICAL GEOGRAPHY. 


51 


comes of the Rain ? Part of it sinks into the earth, 
and afterwards comes out again in springs; part 
of it flows off at once into brooks and rivers; but 
of the total rainfall upon the land only about a third 
or fourth part appears finally to he discharged by 
rivers into the sea, the rest being lost by evaporation. 

114. Here, then, are two distinct courses which 
the rain takes on reaching the earth—one below 
ground, and one above. It will be most convenient 
to follow the underground portion first. 

II. How Springs are formed. 

115. A little attention to the soils and rocks 
which form the surface of a country will show that 
they differ greatly from each other in hardness, and 
in texture or grain. Some are quite loose and 
porous, others are tough and close-grained. They 
consequently differ much in the quantity of water 
they allow to pass through them. A bed of sand, 
for example, is pervious — that is, will let water 
sink through it freely, because the little grains of 
sand lie loosely together, touching each other only 
at some points, so as to leave empty spaces between. 
The water readily finds its way among these empty 
spaces. In fact, the sand-bed may become like a 
kind of sponge, quite saturated with the water which 
has filtered down from the surface. A bed of clay, 
on the other hand, is impervious ; it is made up of 
very small particles fitting closely to each other, and 
therefore offering resistance to the passage of water. 


52 


PHYSICAL GEOGRAPHY. [circulation 


Wherever such a bed occurs, it hinders the free 
passage of the water, which, unable to sink through 
it from above on the way down, or from below on 
the way up to the surface again, is barred back by 
the clay, and forced to find another line of escape. 

116. Sandy soils are dry because they allow the 
rain at once to sink through them ; clay soils are wet 
because they retain the water, and prevent it from 
freely descending into the earth. 

117. When water from rain or melted snow sinks 
below the surface into the soil, or into rock, it does 
not remain at rest there. Where a deep hole is dug 
in the ground, the water which lies between the 
particles of the soil or rock begins to trickle out of 
the sides of the excavation, and gathers into a pool 
in the bottom. If the water is baled out, it still 
keeps oozing from the sides, and the pool is ere long 
filled again. This shows that underground water 
will readily flow into any open channel which it can 
reach. 

118. Now the rocks beneath us, besides being in 
many cases porous in their texture, such as sandstone, 
are all more or less traversed with cracks, or “joints ” 
as they are called—sometimes mere lines, like those 
of a cracked window-pane, but sometimes wide and 
open clefts and tunnels. These numerous channels 
serve as passages for the underground water. Hence, 
although a rock may be so hard and close-grained 
that water would hardly soak through it at all, yet if 
it be much cracked or jointed, it may allow a large 


OF WATER.] PHYSICAL GEOGRAPHY. 


53 


quantity of water to pass through. Limestone, for 
example, is a very hard rock, through the grains of 
which water can make but little way; yet it is 
full of joints, which are often so wide as to give 
passage to a great deal of water. 

119. In hilly districts, where the surface of the 
ground has not been brought under the plough, 
many places are marshy and wet, even when the 
weather has long been dry. The soil everywhere 
around has perhaps been baked quite hard by the 
sun; but these places remain still wet, in spite of 
the heat, because water must there be oozing out of 
the ground. It is this constant outcome of water 
from below which keeps the ground wet and marshy. 
In other places the water does not merely soak 
through the ground, but comes gushing out as a 
Spring. 

120. Springs are the natural outlets for under¬ 
ground water. But we may ask, Why should this 
water have any outlets 1 When once it has sunk 
below the surface, what should ever cause it to rise 
again ? 

121. The following diagram (Fig. 5) represents the 
way in which many rocks lie with regard to each 
other, and in which they may be seen in many a 
long deep trench or section, such as a valley or river 
ravine, a railway cutting or quarry. They are 
arranged in flat layers or beds. Let us suppose 
a to be a layer of some impervious rock, like clay, 
and b another layer of a porous material, like sand. 


54 


PHYSICAL GEOGRAPHY. [cikculation 


The rain which falls on the surface of the ground, 
and sinks through the upper bed ( b) will be arrested 
by the lower one (a), and made either to gather 
there or to find its escape along the surface of that 



Fig. 5.—Origin of Surface Springs. 


lower bed. If a hollow or valley should have its 
bottom below the level of the line along which the 
water flows, springs will issue along the sides of the 
valley, as shown at s s in the woodcut. The line of 
escape may be either, as in this case, the junction 
between two different kinds of rock, or some of the 
numerous joints already referred to. Whatever it be, 
the water cannot help flowing onward and down¬ 
ward, as long as there is any passage by which it 
can find its way; and the rocks underneath are 
usually so full of cracks that it has no difficulty in 
doing so. 

122. But a great deal of the underground water 
must no doubt descend far below the level of the 
valleys, and even below the level of the sea. And 
yet, though it should descend to a considerable depth, it 
comes at last to the surface again. To realise clearly 
how this takes place, let us in imagination follow a 
particular drop of water, from the time when it sinks 
into the earth as rain to the time when, after long 











OF WATER.] PHYSICAL GEOGRAPHY. 


55 


journeying up and down in the bowels of the earth, 
it once more reaches the surface. It soaks through the 
soil together with other drops, and joins some feeble 
trickle, or some more ample flow of water, which works 
its way through crevices and tunnels of the rocks. 
It may descend to a depth of several hundred feet in 
this way, until it reaches some rock through which it 
cannot readily make farther progress. All this while 
it has been followed by other drops, coursing after it 
through its winding passage down to the same barrier 
at the bottom. The union of all these drops forms 



Fig. 6.—Section of part of a district to show the origin of deep-seated 
Springs. The numerous joints in the rocks lead the water down into a 
main channel, by which it re-ascends to the surface as a spring at s. 


an accumulation of water, which is continually pressed 
by what is descending from the surface. Unable to 
work its way downward, the pent-up water must try 



56 


PHYSICAL GEOGRAPHY. [circulation 


to find escape in some other direction. By the pres¬ 
sure from above it is driven through other cracks 
and passages, winding up and down until at last it 
comes to the surface again. It breaks out there as 
a gushing spring (see Physics Primer, Art. 23). 

123. Thus each of the numerous springs which 
issue out of the ground is a proof that there is a cir¬ 
culation of water underneath, as well as upon the 
surface of the land. But besides these natural out¬ 
lets, other proofs are afforded by the artificial 
openings made in the earth. Holes, called WeUs, 
are actually dug to catch this water as it oozes 
or filters through subterranean rocks. Mines, pits, 
quarries, and deep excavations of any kind, are 
usually troubled with it, and need to be kept dry 
by powerful engines that remove the water. But 
so abundant is the underground circulation that the 
water gathers almost as fast as it is pumped out. 

III. The work of Water underground. 

124. No form of water seems purer than the clear 
crystal spring as it comes bubbling out of the earth. 
Water, perfectly pure in a chemical sense, should 
consist only of the two elements Oxygen and Hydro¬ 
gen. But in the water of every spring, no matter 
how clear and sparkling it may be, there is some¬ 
thing else. If perfectly pure water were boiled 
down, the whole of it might be driven off in steam, 
and nothing would be left behind. But it is hardly 
possible to get water that is absolutely pure. Even 


OF WATER. 1 PHYSICAL GEOGRAPHY. 


57 


rain, which is probably the purest natural form of 
water, takes up a little impurity from the air. When 
a quantity of spring water is boiled down, a residue of 
solid matter is left behind. Sparkling transparency 
is thus no guide to the chemical purity of the water 
(see Chemistry Primer, Arts. 20, 21). 

125. If, now, rain is water nearly in a state of 
purity, and if after journeying underground it comes 
out again in springs, always containing more or less of 
something besides mere water, it must get this addi¬ 
tion from the rocks through which it travels. The 
substances so taken up are not visible to the eye, 
for they are held in what is called chemical solution 
(Chemistry Primer, Art. 23). When a few grains of 
salt or sugar are put upon a plate, and water is 
poured over them, they are dissolved in the water 
and disappear. They enter into union with the 
water. We can no longer see them, but may recog¬ 
nise their presence by the taste which they give to 
the water that holds them in solution. 

126. Eain sinking into the soil dissolves a little 
of the earthy substances through which it passes. 
As the water trickles through the subterranean rocks, 
it also dissolves a portion of their materials. But 
soil and solid rock are not acted on quite so easily, 
or in the same way, as salt or sugar. Let us try to 
understand how they are eaten away by water. 

127. We have already learnt that one of the 
important ingredients in the air is carbonic acid 
gas, and that this substance is both abstracted from 

E 


58 


PHYSICAL GEOGRAPHY. [circulation 


and supplied to the air by plants and animals (Art. 
45). In descending through the atmosphere, rain 
absorbs a little air. As ingredients of the air, a 
little carbonic acid gas, particles of dust and soot, 
noxious vapours, minute organisms, and other sub¬ 
stances floating in the air, are caught up by the de¬ 
scending rain, which in this way, as it were, washes 
the air, and tends to keep it much more wholesome 
than it would otherwise be. Those who live in a 
town should make the experiment of catching a little 
rain in a carefully-cleaned dish, and evaporating some 
of it to dryness on a clean piece of glass. They will 
find a little film left behind which, on being largely 
magnified, will be seen to be full of little flakes and 
fragments of town soot and dust, with occasional 
crystals of salt or some other mineral substances 
present in the air. 

128. But rain not merely picks up impurities from 
the air,—it gets a large addition when it reaches the 
soil. In a handful of earth from a field or a garden 
you may notice the tiny fibres of decaying roots and 
leaves. Soil contains always more or less organic 
matter—that is, some of the substance of dead plants 
and animals. And with this substance are associated 
carbonic and some other acids (Arts. 45, 138, 156). 
If you put some of the soil on a piece of iron and 
thrust it into the fire, you will burn off the organic 
matter, remove the carbonic acid, and change the 
colour of the soil. 

129. Armed with the carbonic acid which it gets 


OF WATER.] PHYSICAL GEOGRAPHY. 


59 


from the air, and with the larger quantity of this 
acid and of various other acids, supplied by the de¬ 
caying organic matter, which it abstracts from the 
soil, rain-water is prepared to attack rocks, and to eat 
into them in a way which pure water could not do 
(see Chemistry Primer, Experiment 28). 

130. Water containing these acids has a remark¬ 
able effect on many rocks, even on some of the very 
hardest. It dissolves more or less of their substance, 
and removes it. When it falls, for instance, on lime¬ 
stone, it dissolves and carries away some of the rock 
in solution, though still remaining clear and limpid. 
In countries where limestone is an abundant rock, 
this action of water is sometimes singularly shown in 
the way in which the surface of the ground is worn 
into hollows. In such districts, too, the springs are 
apt to be hard —they contain so much mineral 
matter in solution as to require more soap for domestic 
purposes; whereas rain-water and springs which 
contain little impurity, and require comparatively 
little soap, are termed soft (Chemistry Primer. Art. 
26). 

131. Many of the substances abstracted by the 
water of springs are useful in the life of plants and 
of animals. Lime, salt, and iron, for example, are 
all brought up in spring-water, and are all of great 
value. Lime furnishes material for the bones of 
animals, and iron supplies the colouring matter of 
their blood. We obtain, indeed, most of what we 
need of these materials from our solid food; yet 


60 PHYSICAL GEOGRAPHY. [circulation 

spring-water, in so far as it contains them, is healthier 
for drinking and cooking than rain-water would be. 
132. As every spring throughout the world is busy 



Fig. 7.—Subterranean Channel dissolved out of Limestone-rock by Water. 


bringing up materials of some kind to the surface, 
it is plain that the amount of rock dissolved and 
removed must in the end be very great. Channels 



OF WATER.] PHYSICAL GEOGKAPHY. 


61 


and tunnels are formed underground especially in 
limestones, for the water is always eating away a 
little of the surface over which it flows, thereby 
widening the cracks and crevices, and converting 
them by degrees into wider passages. In this way 
large caverns many feet high and many miles long 
have been formed underneath the surface in different 
parts of the world. Here and there, too, the roofs of 
these caverns fall in, and rivers, engulfed in the 
subterranean passages, sometimes flow a long way 
there before they once more make their way to the 
surface (Fig. 7). 

IV. How the surface of the Earth crumbles 
away. 

133. When a stone building has stood for a few 
hundred years, the smoothly-dressed face which its 
walls received from the mason is usually gone. The 
stones are worn into holes and furrows, the carvings 
over window and doorway are so wasted that perhaps 
one cannot make out what they were meant to repre¬ 
sent. This time-eaten character of old masonry is 
so familiar that we always look for it in an old 
building, and when it is absent we are inclined to 
doubt whether the building can really be old. 

134. Again, in the burying-ground surrounding a 
venerable church the tombstones are more and more 
mouldered the older they are. Sometimes, especially 
on marble slabs exposed to the open air in towns, 
the inscriptions dating from more than two or three 


62 


PHYSICAL GEOGRAPHY. [circulation 


generations back are so greatly wasted that they no 
longer tell whose names and virtues they were set up 
to commemorate. 

135. This crumbling away of hard stone with the 
lapse of time is a common familiar fact. But have 
you ever wondered why it should be so ? What 
makes the stone decay, and what purpose in nature 
is served by the process ? 

136. In the case of buildings and other works of 
human construction, the nature and rate of decay can 
be noted and measured, for the stones, rough and 
worn as they may be now, left the hands of the 
masons with smoothly-dressed surfaces. But the 
decay is not confined to human erections. What we 
see there so strikingly is only a specimen of what 
goes on over the whole face of the world. 

137. You should take every opportunity of verify¬ 
ing, by your own personal observation, the statement 
that the surface of the earth is crumbling away. 
Examine all the old buildings and exposed pieces of 
sculpture within your reach. Look at the cliffs and 
ravines, the crags and water-courses, in your neighbour¬ 
hood. At the base of each cliff you may find the ground 
cumbered with blocks and heaps of lesser fragments 
that have fallen from the rocks above. In countries 
where the winters are cold, much damage is done to 
cliffs by frost (Art. 140), and one may sometimes see 
there the fresh scar whence a new mass has been 
detached to add to the pile of ruins below. In spite, 
therefore, of their apparent steadfastness, even the 


OF WATER.] PHYSICAL GEOGRAPHY. 


63 


hardest stones are really crumbling down, for where- 
ever exposed to the air they are liable to decay. 
Now let us see how this change is brought about. 

138. First of all, we must return for a moment to 
the action of carbonic acid and organic acids, which 
has been already (Arts. 128-130) described. We have 
found that rain-water, by means of the carbonic and 
other acids which it abstracts from the air and soil, 
is enabled to eat away some parts of the rocks be¬ 
neath. The rain which rests upon or flows over the 
surface of the ground acts in a similar way. It 
dissolves out, little by little, such portions of the 
rocks as it can remove. In the case of some rocks, 
such as limestone, the whole, or almost the whole, 
of the substance of the rock is soluble. In other 
kinds, the portion dissolved is the cementing material 
whereby the mass of the rock was bound together; 
so that when it is taken away, the rock crumbles 
into mere earth or sand, which is readily washed 
away by the rain. Hence one of the causes of the 
mouldering of stone is the action of the acids taken 
up by rain. 

139. In the second place, the oxygen of the por¬ 
tion of air contained in rain-water helps to decompose 
rocks. When a piece of iron has been exposed for a 
time to the weather, in such a damp climate as that 
of Britain, it rusts. In the course of years iron 
railings get crusted with a dirty yellow or brown 
powder, which seems to eat into them till they are 
quite worn through. This yellow powder or rust 


64 


PHYSICAL GEOGRAPHY. [circulation 


is a compound substance, formed by the union of 
oxygen with iron. It continues to be formed as long 
as any of the unrusted iron remains within reach, 
since, as each crust of rust is washed off, a new layer 
of iron is laid open to the attacks of the oxygen. 
What happens to an iron railing or a steel knife 
happens also, though not so quickly nor so strongly, 
to many rocks. They, too, rust by absorbing oxygen. 
A crust of corroded rock forms on their surface, and 
when it is removed by rain, wind, or frost, a fresh 
layer of rock is reached by the ever-present and active 
oxygen. 

140. In the third place, the surface of many parts 
of the world is made to crumble down by means of 
frost. Those who live in climates where the tem¬ 
perature falls below the freezing-point are familiar 
with some of the effects of frost. When the cold 
gets very keen, pipes full of water burst, and jugs 
filled with water are cracked from top to bottom. 
The reason of this lies in the fact that water expands 
in freezing. Ice requires more space than the water 
would do if it remained fluid. When ice forms 
within a confined space, it exerts a great pressure on 
the sides of the vessel or cavity which contains it. 
If these sides are not strong enough to bear the strain 
to which they are put, they must yield, and hence 
they are split open (Physics Primer, Art. 61). 

141. While soil is usually so porous that rain 
readily sinks through it, all rocks are also more or 
less pervious. Even the hardest and densest of them 


OF WATER.] PHYSICAL GEOGRAPHY. 


65 


take in some water. Hence, when winter comes, the 
ground contains moisture, not in the soil merely, but 
in the rocks. As frost sets in, this pervading moist¬ 
ure freezes. Now, precisely the same kind of action 
takes place with each particle of water as in the 
case of a burst water-pipe or cracked jar. It does 
not matter whether the water is collected into some 
hole or crevice, or is diffused among the grains of 
the rocks and the soil. When it freezes it expands, 
and in so doing tries to push asunder the walls 
between which it is confined. 

142. Hence arise some curious and interesting 
effects of frost upon the ground. After a frosty night 
the small stones upon a road or footpath may often 
be seen to have been partly pushed out of their beds. 
As the ground thaws, the surface of the road is 
covered with a layer of fine mud. The frost separates 
the grains of sand and clay by freezing the moisture 
between them, so that when the frozen moisture 
melts, the particles of soil no longer adhere to each 
other, but seem as if they had been pounded down in 
a mortar. Hence frost is of great service to the 
farmer in breaking up the soil, and opening it out 
for the roots and fibres of plants. When a surface 
of rock has been well soaked with rain, and is then 
exposed to frost, the grains of the rock undergo the 
same kind of pressure from the freezing of the water 
in the pores between them. Not being so loose and 
open, however, as those of the soil are, they with¬ 
stand the action of the frost better. Of course, the 


66 


PHYSICAL GEOGRAPHY. [circulation 


most porous rocks, or those which hold most water, 
are most liable to suffer from frost; some of them, 
such as certain kinds of sandstone, being often liable 



Fig. 8.—Waste of a Cliff. 


to rapid decay from this cause. Crust after crust is 
peeled off from the stone, or its grains are loosened 
from each other and washed away by rain. 









OF water.] PHYSICAL GEOGRAPHY. 


67 


143. Again, water freezes not only between the 
component grains of rocks, but in the joints which 
were referred to in Art. 118. How joints help the 
action of frost may be observed on the face of a 
cliff, or in a quarry, where they may be seen as 
nearly vertical lines of fracture, dividing rocks into 
large upright blocks or pillars. They help the 
quarryman to break the rock into the blocks he 
needs to extract, and they are also made use of by 
nature for a similar purpose, and in the following 
way. Joints serve as passages for water in descend¬ 
ing from the surface. Every time the water freezes, 
it tends to push asunder the two sides of the 
joint between which it is confined. After many 
winters, it is at last able to separate them a little; 
then more water enters, and more force is exerted 
in freezing, until at last the block of rock traversed 
by the joint is completely split up. When this 
takes place along the face of a cliff, one of the 
loosened parts may fall down to the bottom of the 
precipice. 

144. This kind of waste is represented in the ac¬ 
companying woodcut (Fig. 8), which gives a section 
of a cliff wherein the rocks are traversed by vertical 
joints. These have been widened along the front, 
until large blocks have been wedged off and have 
fallen to the ground. In countries exposed to severe 
winters, the waste caused by frosts along lines of 
steep cliff is often enormous. 

145. In addition to carbonic acid, oxygen, and 


68 


PHYSICAL GEOGRAPHY. [circulation 


frost, there are still other influences at work by which 
the surface of the earth is made to crumble. For 
example, when, during the day, rocks are highly 
heated by strong sunshine, and during night are 
rapidly cooled by radiation, the alternate expansion 
and contraction caused by the extremes of temperature 
loosen the particles of the stone, causing them to 
crumble away, or even making successive crusts of 
the stone fall off. In very dry climates this cause 
acts powerfully (Art. Gl). The wind, too, by driving 
the loosened parts of the rock away, lays bare the 
parts underneath, and wears down the surface even 
of hard rocks, by driving grains of sand against 
them. The sand wastes of the great deserts of the 
globe are probably due to the gradual decay of the 
rocks in a dry climate with a great daily range of 
temperature, and the subsequent heaping up of the 
crumbled particles by the wind. 

146. And thus we learn that, from a variety of 
causes, solid rocks are liable to continual decay 
and removal. The hardest stone, as well as the 
softest, must yield in the end, and moulder down. 
They do not all, indeed, decay at the same rate. 
Examining more narrowly the wall of an ancient 
building, we may see almost every variety in the 
degree of decay. Some of the stones are hardly 
worn at all, while others may be almost wholly 
gone. If this takes place in a building, we may 
be sure it must take place also in nature, and 
that some cliffs or crags or portions of them will 


OF WATER.] PHYSICAL GEOGRAPHY. 


69 


crumble down faster than others, and will do so in a 
different way. 

147. At first we may be inclined to wonder that 
there should be a general wasting of the surface of 
the land, and to ask ourselves how this should be in 
a world that seems so fair and beautifuL We may 
even be tempted to consider the decay as a misfortune 
hardly to be explained. But instead of being in any 
way calamitous, the mouldering of the surface is in 
reality necessary to make the earth fit to be the 
dwelling-place of plants and animals. To it we owe 
the scooping out of valleys and ravines, and the 
picturesque outlines of crags and hills. Out of the 
crumbled stones all soil is made, and on the forma¬ 
tion and renewal of the soil we depend for our daily 
food. How this is brought about will be told in the 
next Lesson. 

V. What becomes of the crumbled parts of 
Rocks. How Soil is made. 

148. Take up a handful of soil from any field or 
garden, and look at it attentively. It appears to be 
made of particles of sand and clay, with pieces of 
crumbling stone, and probably also a few vegetable 
fibres. Now let us try to learn how these different 
materials have been brought together. 

149. We return again to the general mouldering 
of the surface of the land described in last Lesson. 
The words “ decay,” “ waste,” and others of similar 
meaning, are applied to this process. But in reality, 


70 


PHYSICAL GEOGRAPHY. [circulation 


although the rocks may crumble away, and thereby 
grow less in size year by year, there is no actual loss 
of material to the surface of the earth. The sub¬ 
stance of the rock is not destroyed. It only changes 
its condition and form, and moves into other places. 
What, then, becomes of all the material continually 
being worn from the surface of the land ? 

150. In a former Lesson (Art. 138) we followed 
the chemical action of rain when it dissolves parts 
of rocks. By the constant repetition of the process, 
shower after shower, for years together, the rocks 
become marvellously wasted and worn. But the 
rain has also a mechanical action. 

151. Watch what happens when the first patter¬ 
ing drops of a shower begin to fall upon a smooth 
surface of sand, such as that of a beach. Each drop 
makes a little dint or impression by pressing aside 
the grains of sand. On sloping ground, where the 



Fig. 9.—Prints impressed on Clay or Sand by Drops of Rain. 


drops can run together and flow downward, they are 
able to push or carry the particles of sand or clay 
along. This is called a mechanical action; while 
the actual solution of the particles, as you would 
dissolve sugar or salt, is a chemical action. Each 



OF WATER.] PHYSICAL GEOGRAPHY. 


71 


drop of rain may act in either or both of these 
ways. 

152. We need not be surprised that rain should 
do so much in the destruction of rocks. It not 
only dissolves out some parts of them, leaving a 
crumbling crust on the surface, but it washes away 
this crust, and thereby exposes a fresh surface to 
decay. There is, in this way, a continual pushing 
along of powdered stone over the earth's surface. 
Part of this material accumulates in hollows, and on 
sloping or level ground ; part is swept into rivers and 
lakes; while a considerable proportion in the end is 
carried away into the sea. 

153. It is this crumbled stone which, mingled with 
the remains of plants and animals, forms what we call 
soH or vegetable mould. Soils must obviously differ 
according to the kind of rock out of which they have 
been formed. Sandstone, for example, will give rise 
to a sandy soil ; limestone to a limy or calcareous 
soil; clay-rocks to a clayey soil. 

154. But for this crumbling of the rocks into soil, 
the land would not be covered with verdure as it is, 
for plants get part of their nourishment out of the 
soil. Bare sheets of undecaying stone would give 
no footing for roots. The materials of the stone 
require to be more or less decomposed and broken 
up before plants can get their required nutriment out 
of them. But by the decay of their surface, bare 
rocks are eventually covered with fertile soil all over 
the valleys and plains ; and only where, as in steep 


72 


PHYSICAL GEOGRAPHY. [circulation 


banks and cliffs, they rise too abruptly to let their 
crumbled remains gather upon them, do they stand 
up naked and verdureless. 

155. As the crumbling of the surface of the land 
is always going on, there is a constant formation of 
mould. Indeed, if this were not the case,—if, after 
a layer of mould had been formed upon the ground, it 
were to remain there unmoved and unrenewed,—the 
plants would by degrees take out of it all the earthy 
materials fitted for their support. Becoming in the 
end exhausted, it would no longer support such vege¬ 
tation, at least, as previously lived upon it. But this 
state of things is prevented by the continual renewal 
of the soil, partly owing to the supply of fresh 
materials from the decay of neighbouring rocks or 
stones, partly owing to the decay of the sub-soil or 
decomposing rock below the soil. As the surface 
soil is removed by rain and wind, the decay eats 
down, as it were, into the still unweathered stone 
beneath, and thus the soil is renewed from below, 
as fast perhaps as it is washed away at the surface. 
Even the loose stones in the mould itself are con¬ 
tinually crumbling down and making new earth. 
And thus, day by day, the soil is slowly renewed, 
and the balance required for the continued growth of 
vegetation is preserved. 

156. Plants also help to form and renew the 
mould. They send their roots among the grains 
and joints of the stones, and loosen them. Their 
decaying fibres supply the carbonic and other acids 


OF WATER.] PHYSICAL GEOGRAPHY. 


73 


by which these stones are attacked, and furnish also 
most of the organic matter in the soil. Even com¬ 
mon earth-worms are of great service in mixing the 
soil, burying leaves and twigs so as to hasten their 
decay into mould, and bringing what lies underneath 
up to the surface. 

157. Reflecting upon this decay and renewal of 
soil, we perceive that in reality the whole surface 
of the land may be looked upon as travelling down 
to the sea. The particles worn from the sides and 
crests of the high mountains may take hundreds or 
thousands of years on the journey; they may lie for 
a long time on the slopes; they may then be swept 
down and form part of the soil of the valleys ; thence 
they may be in after years borne away and laid 
down on the bed or bank of a river; but at last 
after many halts by the way, they reach the sea, and 
are spread out as mud and sand over its floor. 

158. In order to form some idea of the extent 
to which the surface of the land is cleared of its 
loose soil, you should notice what takes place after 
heavy rain. Each little brook becomes muddy from 
the quantity of soil washed into it by the rain from 
the neighbouring slopes. The mud that darkens the 
water is made of the finer particles of decomposed 
rocks; the coarser parts are moving along at the 
bottom of the water. Watching these streamlets 
at their work, and remembering that what they are 
doing now they have been doing for ages past, you 
will understand how greatly the surface of a country 

F 


74 


PHYSICAL GEOGRAPHY. [circulation 


may come to be changed by the action of what at 
first seems so insignificant a thing as Rain. 

VI. Brooks and Rivers : Their Origin. 

159. We must now go back to an earlier Lesson 
(Art. 113), where the way in which rain is disposed 
of was referred to. We saw that one part of the 
rain sinks under the ground, and we have traced its 
progress there until it returns to the surface in 
springs. We have now to follow, in a similar way, 
the other portion of the rainfall which flows along 
the surface in brooks and rivers. 

160. A familiar illustration of this subject is 
furnished by a gently sloping road during a heavy 
shower of rain. Suppose that, as the rain begins, we 
take our stand at some part of such a road where 
there is a well-marked descent. At first each of the 
large heavy drops of rain makes in the dust, or sand, 
one of the little dints or rain-prints already described 
(Art. 151). As the shower becomes heavier these rain- 
prints are effaced, and the road soon streams with 
water. Now mark in what manner the water moves. 

161. Looking at the road more narrowly, we 
remark that it is full of little roughnesses—at one 
place a long rut, at another a projecting stone, with 
many more inequalities which our eye could not 
easily detect when the road was dry, but which the 
water at once discloses. Every little dimple and 
projection affects the flow of the water. We see 
how the raindrops gather together into slender 


OF WATER.] PHYSICAL GEOGRAPHY. 


75 


streamlets that course along the hollows, and how 
the jutting stones and pieces of earth seem to turn 
these streamlets now to one side and now to another. 

162. Towards the top of the slope only feeble 
runnels of water are to be seen. But farther down 
they become fewer in number, and at the same time 
larger in size. They unite as they descend; and the 
larger and swifter streamlets at the foot of the descent 
are thus made up of a great many smaller ones from 
the higher parts of the slope. 

163. Now this sloping roadway, with its branching 
rills of rain, coursing down the slope, and uniting 
into larger streams as they advance, shows very well 
the way in which the rain runs off the sloping surface 
of a country or a continent, and we shall return to 
the illustration again. 

164. Why does the water run down the sloping 
road 1 Why does a river flow always in the same 
direction ? It does so for the same reason that a 
stone falls to the ground when it drops out of your 
hand: because it is under the sway of that attrac¬ 
tion towards the centre of the earth to which 
the name of Gravity (Physics Primer, Art. 4) 
is given. Every drop of rain falls to the earth 
because it is drawn downwards by the force of this 
attraction. When it reaches the ground it is still, 
as much as ever, under the same influence; and it 
flows downwards in the readiest channel it can find. 
Its fall from the clouds to the earth is direct and 
rapid; its descent from the mountains to the sea, as 


76 


PHYSICAL GEOGRAPHY. [circulation 


part of a stream, is often long and slow; but the cause 
of the movement is the same in either case. The 
winding to and fro of streams, the rush of their 
rapids, the roar of their cataracts, the noiseless Row 
of their deep sullen currents, are all proofs how para¬ 
mount is the sway of the law of gravity over the 
waters of the globe. 

165. Drawn down, in this way, by the action of 
gravity, all that portion of the rain which does not 
sink into the earth must at once begin to move down¬ 
wards along the nearest slopes, and continue flowing 
until it can get no farther. On the surface of the 
land there are hollows which arrest part of the flow¬ 
ing water, and gather it into Lakes, just as there 
are hollows on the road which serve to collect some 
of the rain into pools. But in most cases they let the 
water run out at the lower end as fast as it runs 
in at the upper, and therefore do not serve as per¬ 
manent resting places for it. Streams that escape 
from lakes go on as before, working their way to the 
sea-shore. So that the course of all streams is a 
downward one; and the sea is the great reservoir 
into which the water of the land is continually 
pouring. 

166. If the surface of a country were a mere long 
smooth ridge, like the roof of a house, the rain would 
quickly flow down on either side into the sea. But 
this is by no means the general character of the 
surface of the land. Mountains, hills, valleys, gorges, 
and lakes give a most uneven and varied outline. 


of WATER.] PHYSICAL GEOGRAPHY. 


77 


But besides these greater inequalities which strike 
the eye at once, even places that seem at first level 
have some slope or some slight unevennesses; just 
as on the road we found that there may be many 
little irregularities of surface which might escape 
notice until the rain revealed them. Water is 
thus a most accurate measurer of the levels of a 
country. It will not flow up a slope nor lie at rest 
upon it, but always seeks the lowest level it can find. 

167. Considering this matter further, we see how 
the rain, though it should fall equally over the whole 
surface of a country, cannot flow equally over that 
surface. The ground being uneven, the rain neces¬ 
sarily runs off into the hollows. It is this unevenness, 
therefore, which causes the rain to collect into brooks,. 
and these into rivers. 

168. The brooks and rivers of a country are thus 
the natural drains whereby the surplus rainfall, not 
required by the soil or by springs, and not returned 
to the atmosphere by evaporation, is led back again 
into the sea. When we consider the vast amount of 
rain that falls on the land, and the enormous number 
of brooks in the higher parts of a country, it seems, 
at first, hardly possible for all these streams to reach 
the sea without overflowing the lower grounds. But 
this does not take place; for when two streams unite 
into one, they do not require a channel twice as 
broad as either of their single water-courses. On 
the contrary, such an union often gives rise to a 
stream which is not so broad as either of the two 


78 


PHYSICAL GEOGRAPHY. [circulation 


from which it flows. But it becomes swifter and 
deeper. In this way thousands of streamlets, as 
they come together in their descent, are made to 
take up less and less room, until the surplus waters 
of a whole vast region are borne into the sea by one 
single river-channel 

169. Some further illustrations of the drainage of 
a country may be taken from the roadway in rain. 
Starting from the foot of the slope, we found the 
streamlets of rain to become smaller and smaller, until 
towards the top there were none at all. If, however, 
we descended the road on the other side of the ridge, 
we should meet with other streamlets coursing down¬ 
hill in the opposite direction. At the summit the 
rain seems to divide, part flowing off to one side, 
and part to the other. 

170. In the same way, were we to ascend some 
river from the sea, we should watch it becoming 
narrower, and branching more and more into tribu¬ 
tary streams, and these again subdividing into almost 
endless little brooks. But taking any of these branches 
and tracing it upward, we should arrive in the end at 
the first beginnings of a little brook, and going a little 
farther would reach the summit, on the other side 
of which all the streams would flow to the opposite 
quarter. The line which separates two sets of streams 
in this way is called the Water-shed or Divide. In 
England, for example, one series of rivers flows into 
the Atlantic Ocean, another into the North Sea. In 
North America many large rivers carry the drainage 


OF WATER.] PHYSICAL GEOGRAPHY. 


79 


of the continent eastward from the Bocky Mountains 
into the Atlantic, and a number of smaller and shorter 
streams descend the western slope into the Pacific 
Ocean. If we trace upon a map a line separating 
all the upper streams of the one side from those of 
the other, that line will mark the water-shed of the 
country or continent. 

171. But there is one important point where the 
illustration of the road in rain quite fails. It is only 
when rain is falling, or immediately after a heavy 
shower, that rills are seen upon the road. When 
the rain ceases, the pools begin to dry up, till the 
road becomes once more firm and dusty. But 
brooks and rivers do not disappear though the rain 
ends. In the heat of summer, when perhaps there 
has been no rain for many days together, the rivers 
still roll on, smaller usually than they were in winter, 
but still with ample flow. What keeps them full 1 
We have already learnt in a former Lesson how this 
question must be answeredrivers are fed by- 
springs as weU as by rain. 

172. Though the weather may be rainless, springs 
continue to give out their supplies of water, and 
these keep the rivers going. But if great drought 
comes, many of the springs—particularly the shallow 
ones —cease to flow, and the rivers fed by them 
shrink in size, or, where they are of small dimensions, 
dry up altogether. This is the case with many of 
the streams in Britain, which are all, comparatively 
speaking, very small. The great rivers of the globe, 


80 


PHYSICAL GEOGRAPHY. [circulation 


such as the Mississippi, drain such vast territories 
that any mere local rain or drought makes no sensible 
difference in their mass of water. 

173. In some parts of the world, however, the 
rivers are larger in summer and autumn than they 
are in winter and spring. The Rhine, for instance, 
begins to rise as the heat of summer increases, and 
to fall as the cold of winter comes on. This happens 
because the river has its source among snowy moun¬ 
tains. Snow melts rapidly in summer, and the 
water which streams from it finds its way into brooks 
and rivers, which are thereby greatly swollen. In 
winter, on the other hand, the snow remains un¬ 
melted ; the moisture which falls from the air upon 
the mountains is chiefly snow; and the cold is such 
as to freeze the brooks. Hence the supplies of water 
at the sources of these rivers are, in winter, greatly 
diminished, and the rivers themselves become pro¬ 
portionately smaller. 

174. Summary. —To sum up what has been stated 
in this and the preceding Lessons regarding the circu¬ 
lation of water: From the highest parts of the land 
down to the sea, water is continually travelling down¬ 
ward. It does not pour over the whole surface, but 
gathers into the hollows, where it forms streams 
that wind to and fro, always seeking a lower level, 
till at last they lose themselves in the sea. From 
the sea, as well as from all surfaces of water on the 
land, vapour is constantly rising into the air, whence 
it is brought back and condensed upon sea and land 


OF WATER.] PHYSICAL GEOGRAPHY. 


81 


as rain or snow, to moisten and fertilise the soil, to 
supply water for springs and underground circulation, 
and to feed the streams that flow downward into the 
sea. This circulation of water goes on without 
ceasing. 

VII. Brooks and Rivers: Their work. 

175. In the first pages of this little book we were 
engaged in watching the doings of a river. Let us now 
again return to the same scene, but before the storm 
which was then described. The river is not yet 
swollen with the sudden and heavy rain. It flows 
gently over its pebbly channel, not covering the 
whole of it perhaps, but leaving banks of gravel and 
pools of water, between which the clear current, much 
diminished by drought, winds its way. The river 
seems to be doing nothing else than lazily carrying 
the surplus water of the land towards the sea. You 
may be surprised to be told that it has any work to 
do, and even now is doing it. 

176. But consider whence the water of the river 
comes. We have found that river-water is largely de¬ 
rived from springs, and that all spring-water contains 
more or less mineral materials dissolved out of the 
rocks. Every river, therefore, is carrying not merely 
water, but large quantities of mineral matter, into the 
sea. It has been calculated, for instance, that the Rhine 
in one year carries into the North Sea lime enough 
to make three hundred and thirty-two thousand 
millions of oyster shells. This chemically-dissolved 


82 


PHYSICAL GEOGRAPHY. [circulation 


material is not visible to the eye, and in no way 
affects the colour of the water. At all times of the 
year, as long as the water flows, this invisible trans¬ 
port of some of the materials of rocks must be 
going on. 

177. But let us now again return to our river in 
flood, when the water is no longer clear, but dull and 
dirty. We found this discoloration to arise from 
mud and sand suspended in the water. For hours 
the swollen, turbid torrent rolls down its channel, 
and during that time many tons of gravel, sand, and 
mud must be swept past. Over and above the 
mineral matter in chemical solution, therefore, the 
river is hurrying seaward with vast quantities of 
other and visible materials. The stones on the 
bottom of the channel may sometimes even be heard 
knocking against each other, as they are rolled for¬ 
wards by the flood. And thus it is clear that one 
great part of the work of rivers must be to trans¬ 
port the mouldered parts of the land which are car¬ 
ried into them by springs or by rain. 

178. But rivers, too, help in the general destruc¬ 
tion of the surface of the land. Of this we may 
readily be assured by looking at the sides or bed 
of a stream when the water is low. Where the 
stream flows over hard rock, we find the rock is 
smoothed and ground away; and the stones lying in 
the water-course are all more or less rounded and 
smoothed. When these stones were originally broken 
by frosts or otherwise from crags or cliffs, they were 


OF WATER.] PHYSICAL GEOGRAPHY. 


83 


sharp-edged, like those that gather at the foot of any 
crumbling precipice or steep bank of rock. But 
when they fell, or were washed into the river, they 
began to be rolled and rubbed, until, as their sharp 
edges were ground away, they were worn into the 
smooth rounded forms of ordinary gravel. 

179. While the stones are ground down, they at 
the same time grind down the rocks that form the 
sides and bottom of the river-channel over which 
they are driven. In some of the eddies of the stream, 
the stones are kept moving round, until they actually 
excavate deep round cavities, called pot-holes, in 
the solid rock. When the water is low, as during 
the droughts of summer, some of these cavities are 
laid bare, and we may then observe how well they 
have been polished. Their general appearance is 
shown in Fig. 10. 

180. Now, it is clear that two results must follow 
from this ceaseless wear and tear of rocks and stones 
in the channel of a stream. In the first place, a great 
deal of mud and sand must be produced; and, in the 
second place, the bed of the river must be ground 
down so as to become deeper and wider. The sand 
and mud are added to the other similar materials 
washed into the streams by rain from the mouldering 
surface of the land. By the deepening and widening 
of the water-courses, such picturesque features as 
gorges and ravines are excavated out of solid rock. 

181. Let us next inquire what becomes of all the 
mud, sand, gravel, and blocks of stone which rivers 


84 


PHYSICAL GEOGRAPHY. [circulation 


are continually transporting. For this purpose look 
again at the channel of a river in summer. It is 
covered with sheets of gravel in one place, beds of 



Fiq. 10.—Pot-holes excavated by a Stream in the Rocks of its Bed. 


sand in another, while here and there a piece of hard 
rock sticks up through these different kinds of river- 
stuff. Watch some portion of the loose materials, 







OF WATER.] PHYSICAL GEOGRAPHY. 


85 


and you may observe it to be continually shifting. 
A patch of gravel may remain apparently motionless, 
but at least the upper grains of sand are always 
changing as the water covers and moves them. In 
fact, the loose materials over which the river flows 
are somewhat like the river itself. We may come 
back after many years and find the river still there, 
with its ripples and eddies and gentle murmuring 
sound. But though the river has been there con¬ 
stantly all the time, its water has been changing 
every minute, as we can watch it changing still. 
So, although the channel is always more or less 
covered with loose materials, these are not always 
the same. They are perpetually being pushed on¬ 
ward, and others, from higher up the stream, come 
behind to take their place. 

182. It is not in the bottoms of the rivers, then, 
that the material worn away from the surface of the 
land can find any lasting rest. And yet the rivers 
do get rid of a good deal of this material as they roll 
along. You have, perhaps, noticed that a river is 
often bordered with a strip of flat plain, the surface 
of which is only a few feet above the level of the 
water. Most of our rivers have such margins, and, 
indeed, seem each to wind to and fro through a long, 
level, meadow-like plain. Now this plain is really 
made up of the loam, sand, or gravel which the river 
has carried along. During floods each river, swollen 
and muddy, rises above its banks, and spreads over 
the low ground on either side. Whenever this takes 


86 


PHYSICAL GEOGRAPHY. [circulation 


place, the overflowing water moves more slowly over 
the flats ; and, its current being thus checked, it can¬ 
not hold so much mud and sand, but allows some of 
these materials to settle down on the bottom. In 
this way, the overflowed tracts have a coating of soil 
laid over them by the river, and when the waters 
retire, this coating adds a little to the height of the 
plain. The same thing takes place year after year, 
until by degrees the plain is so far raised that the 
river, which all this while is also busy deepening its 
channel, cannot overflow it even at the highest floods. 
In course of time the current, as it winds from side to 
side, cuts away slices of the plain and forms a newer 
plain at a lower level. And thus a series of terraces 
is gradually made, rising step by step above the river 
(Fig. 11). 



Fio. 11.—Section of the successive Terraces (1, 2, 3) of Sand, Earth, and 
Gravel formed by a River along a Valley (s—s). 


183. Still, the laying down of its sand and mud by 
a river to form one or more such river-terraces is, 
after all, only a temporary disposal of these materials. 
They are still liable to be carried away, and in truth 
they are carried off continually, as the river eats away 
its banks. 

184. When the current of a river is checked on 







OF WATER.] PHYSICAL GEOGRAPHY. 


87 


entering the sea or a lake; the feebler flow of the water 
allows the sand and mud to sink to the bottom. By 
degrees some portions of the bottom come in this 
way to be filled up to the surface of the river, and 
wide flat marshy spaces are formed on either side 
of the main stream. During floods these spaces are 
overflowed with muddy water, in the same way as in 
the case of the valley plains just described, and a 
coating of mud or sand is laid down on them, until 
they slowly rise above the ordinary level of the river, 
which winds about among them in endless branching 
streams. Vegetation springs up on these flat swampy 
lands ; animals, too, find food and shelter there; and 
thus a new territory is made by the work of the 
river. 

185. These flat river-formed tracts are called 
Deltas, because the one which was best known to 
the ancients—that of the Nile—had the shape of 
the Greek letter A (delta) (Fig. 12). This is the 
general form which is taken by accumulations at the 
mouths of rivers; each flat delta narrows towards 
the land and broadens towards the sea. Some of 
them are of enormous size ; the delta of the Ganges 
and Brahmaputra, for example, covers an area of be¬ 
tween 50,000 and 60,000 miles, or about as large as 
England and "Wales. 

186. Each delta, then, is made of materials worn 
from the surface of the land, and brought down by 
the river. And yet vast though some of these Deltas 
are, they do not show all the materials which have 


88 


PHYSICAL GEOGRAPHY. [circulation 


been so worn away. A great deal is carried farther 
out and deposited on the sea-bottom; for the sea is 



Fig. 12.—Delta of the Nile. 


the great basin into which the spoils of the land are 
continually borne. 

VIII. Snowfields and Glaciers. 

187. Having now followed the course taken by 
the water which falls on the land as rain, we come 
to that taken by snow (Art. 90). 

188. On the lower mountain groups of Central 
and Southern Europe—such, for instance, as the 
Harz and Auvergne mountains—snow sometimes lies 
thickly during winter, but disappears in summer. 
On the tops of some of the highest mountains in 










OF WATER.] PHYSICAL GEOGRAPHY. 


89 


Britain, in shady clefts facing northwards, deep snow- 
wreaths may be found even in the heat of summer, 
though only in such cool and sheltered spots does it 
remain unmelted. 

189. But in the Alps, in Norway, in the Hima¬ 
laya chain, and in other parts of the world, the 
peaks and higher shoulders of the mountains gleam 
white all the year with unmelted snow. Hardly 
anything in the world will impress you so much 
as the silence and grandeur of these high snowy 
regions. Seen from the valleys, the mountains 
look so vast and distant, so white and pure, yet 
catching up so wonderfully all the colours which 
glow in the sky at morn or even, that they may 
seem to you at first rather parts of the heaven above 
than of the solid earth on which you live. But it is 
when you climb up fairly into their midst that their 
wonderful stateliness comes full before you. Peaks 
and pinnacles of the most dazzling whiteness glisten 
against the dark blue of the sky, streaked here and 
there with lines of purple shadow, or with knobs of 
the dark rock projecting through the white mantle 
which throws far and wide its heavy folds over ridge 
and slope, and sends long tongues of blue ice down 
to the meadows and vineyards of the valleys. There 
is a deep silence over this high frozen country. Now 
and then, a gust of wind brings up from the far 
distance the sound of some remote waterfall, or the 
dash of a mountain torrent. At times, too, there 
comes a harsh roar as of thunder, when some mass 


90 


PHYSICAL GEOGRAPHY. [circulation 


of ice or snow, loosened from the rest, shoots down 
the precipices. But these noises only make the 
silence the deeper when they have passed away. 

190. Let us now inquire into the origin of this 
lonely and lifeless ice-world. Why should snow ever¬ 
lastingly wrap round the shoulders and summits of 
the mountains ? Of what use is snow on the low 
ground as well as among the heights ? 

191. The higher parts of the atmosphere, as already 
noticed (Art. 89), are extremely cold. In the far north 
and the far south, around those two opposite parts of 
the earth’s surface called the Poles, the climate is 
likewise so intensely cold as to give rise to dreary 
expanses of ice and snow, where sea and land are 
frozen, and where the heat of summer is able only 
partially to thaw the accumulated snow of the rest of 
the year. Between these two polar tracts of cold, 
wherever mountains are lofty enough to rise into the 
high parts of the atmosphere, where the temperature 
is usually below the freezing-point, the vapour con¬ 
densed from the air falls upon them, not as rain, but 
as snow. Their heads and upper heights are thus 
covered with perpetual snow. In such high moun¬ 
tainous regions, the heat of the summer always melts 
the snow from the lower hills, though it leaves the 
higher part still covered. There is a not very 
definite limit below which the snow disappears in 
summer, but above which it never wholly departs 
from year to year. This limit is called the snow¬ 
line, or the limit of perpetual snow. Its height 


OF water.] PHYSICAL GEOGRAPHY. 


91 


varies in different parts of the world. It is highest 
in the warmer regions on either side of the equator, 
where it reaches to 15,000 feet or more above the 
sea. In the cold polar tracts, on the other hand, it 
approaches the sea-level. In other words, while in 
the polar tracts the climate is so cold that perpetual 
snow is found even close to the sea-level, the 
equatorial regions are so warm that we must climb 
to a height of some three miles to reach the cold 
layers of the air, wherein snow can remain all the 
year. 

192. Those who live in a country where the winter 
temperature falls to the freezing-point of water have 
opportunities of seeing a snowstorm. What a con¬ 
trast it presents to a rainstorm! At first a few 
flakes begin to show themselves drifting through the 
air, and falling so silently that if we did not see 
them, we should not know that precipitation of any 
kind was going on in the air. By degrees the flakes 
grow more in number and larger in size, until the 
ground begins to whiten. As hours go on, the whole 
country becomes buried under a white pall, perhaps 
six inches or more in thickness. And yet, except the 
whistling of the bitter wind, we may hear no sound 
from the outer air. Had the fall been of rain instead 
of snow, how monotonous would have been the noise 
of the patter of the drops, and the drip and trickle 
of running water everywhere ! In that case too the 
roads and fields would still have been visible, for 
each drop of rain, instead of remaining where it fell, 


92 


PHYSICAL GEOGRAPHY. [circulation 


would either have sunk into the soil or have flowed 
off into the nearest brook. But each snowflake, on 
the contrary, lies where it falls, unless it happens to 
be caught up and driven on by the wind to some 
other spot where it can finally rest. Bain disappears 
from the ground as soon as it can; snow stays still 
as long as it can. 

193. This marked difference of behaviour must 
obviously lead to still further differences in the work 
done by these two forms of water. We have fol¬ 
lowed the progress of the rain; now let us try to 
find out what becomes of the snow. 

194. In a country where there is no perpetual 
snow this question is easy enough to answer. Each 
fall of snow in winter time remains on the ground as 
long as the air is not warm enough to melt it. Eva¬ 
poration, indeed, goes on from a surface of snow 
and ice, as well as from water; so that a layer of 
snow would in the end disappear by being absorbed 
into the air as vapour, even though none of it had 
previously been melted into running water. But it 
is by what we call a thaw that snow in temperate 
climates is chiefly dissipated—that is, by a rise in 
temperature, and a consequent melting of the 
snow. When the snow melts, the water, thereby let 
loose, sinks into the soil and flows off into brooks, 
in the same way as rain. Its after-course needs 
not to be followed, for it is the same as that of rain. 
We may bear in mind, however, that if a heavy fall 
of snow should be quickly thawed, a large quantity 


OF WATER.] PHYSICAL GEOGRAPHY. 


93 


of water will be let loose over the country, and the 
brooks and rivers will rise rapidly in flood. Great 
destruction may thus be caused by the sudden rise of 
rivers and the overflowing of their banks (Art. 173). 

195. In regions of perpetual snow, where the 
heat of summer cannot melt all the snow that falls 
there in the year, what other way of escape is open to 
the frozen moisture 1 That it must have some means 
of taking itself off the mountains is clear enough; 
for if it had not, and if it were to accumulate there 
from year to year and from century to century, 
the mountains would grow into vast masses of snow, 
reaching far into the sky, and spreading out on all 
sides, so as to bury by degrees the low lands around. 
But nothing of this kind takes place. These solemn 
snowy heights wear the same unchanged look from 
generation to generation. There is no burying of 
their well-known features under a constantly increas¬ 
ing depth of snow. 

196. As the surplus rainfall flows off by means of 
rivers, so the surplus snowfall above the snow-line 
flows off by means of what are called Glaciers. 

197. When a considerable depth of snow has accu¬ 
mulated, the pressure of the overlying mass upon the 
lower layers squeezes them into a firm condition. 
The surface of the ground on which the snow gathers 
is usually sloped in some direction, seldom quite flat. 
Among the high mountains, indeed, the slopes are 
often highly inclined or precipitous. As snow gathers 
deeply on the mountains, the force of gravity event- 


94 


PHYSICAL GEOGRAPHY. [circulation 


ually overcomes the tendency of the pressed snow to 
remain where it is, and the snow then begins to creep 
down the slope. From one slope it passes on down¬ 
wards to the next, joined continually by other sliding 
masses from neighbouring slopes, until they all unite 
into one long tongue which creeps slowly down the 
main valley to a point where it melts. This tongue 
from the snowfields is a Glacier. It really drains 
these snowfields of their excess of snow as much as 
a river drains a district of its excess of water. 

198. But the glacier which comes out of the snow¬ 
fields is itself made not of snow, but of ice. The 
snow, as it slides downward, is pressed together into 
ice. Each snowflake is made of little crystals of ice 
(Art. 88). A mass of snow is thus only a mass of 
minute crystals of ice with air between. Hence, when 
the snow is pressed together, the air is squeezed out, 
and the previously separated crystals of ice freeze 
together into a solid mass. Most schoolboys in 
temperate climates know what snowballs are, and 
that they can be made very hard by squeezing them 
firmly between the hands. The more tightly the 
snow is pressed the harder it gets. In making a 
hard snowball, therefore, you are treating the snow 
somewhat in the same way as nature treats it in 
making a glacier out of the eternal snows. You are 
pressing out the air, and allowing the little particles 
of ice to freeze to each other and to form a compact 
piece of ice. But you cannot squeeze nearly all the 
air out; consequently the ball, even after all your 


OF WATER.] PHYSICAL GEOGRAPHY. 


95 


efforts, is still white from the imprisoned air. Among 
the snowfields, however, the pressure is immensely 
greater and more prolonged than yours; the air is 
more and more pressed out, and at last the snow 
becomes clear transparent ice. 

199. A glacier, then, is a river, not of water, but of 
ice, coming down from the snowfields. It descends 
sometimes a long way below the snow-line, creeping 
down very slowly along the valley which it covers 
from side to side. Its surface all the time is melting 
during the day in summer, and streams of clear water 
gush along the ice, but these are frozen and silent 
at night. At last it reaches some point in the valley 
beyond which it cannot go, for the warmth of the 
air there melts the ice as fast as it advances. So 
the glacier ends, and from its melting front streams 
of muddy water unite into a foaming river, which 
bears the drainage of the snowfields far down into 
the plains, and thence to the sea. 

200. In the accompanying woodcut (Fig. 13) some 
of the chief characters of a glacier are shown. In the 
distance rise the snowy heights, among which the 
snowfields lie. From either side the snow is drained 
off into the main valley, where it forms the glacier, 
which winds with all the windings of the valley till 
it ends abruptly, and a river gushes out from the 
melting end of the ice. 

201. We may be sure that in this constant move¬ 
ment from the high snowfields down into the valleys, 
a glacier must be doing work of some kind. A river, 



Fig. 13. —View of a Glacier, with its Moraines, Perched Blocks, ice-worn 
Bosses of Rock, and escaping River. 

A glacier performs operations of a similar nature, but 
in a very different way. 

2 02. When stones fall into a river they sink to 
the bottom, and are pushed along there by the cur¬ 
rent. When mud enters a river it remains suspended 
in the water, and is thus carried along. But the ice 
of a glacier, though it behaves, on the great scale, 


96 PHYSICAL GEOGRAPHY. [circulation 


as we have seen (Arts. 175-186), wears down the 
sides and bottom of its channel, and thus digs out a 
bed for itself in even the hardest rock, as well as in 
the softest soil. It sweeps down, too, a vast quantity 
of mud, sand, and stones from the land to the sea. 



OF WATER.] PHYSICAL GEOGRAPHY. 


97 


like what is called a viscous or half-fluid body, 
moulding itself to the form of the valley down which 
it moves, is nevertheless a hard brittle substance. 
Stones and mud which fall upon it from the cliffs 
and slopes above do not fall into it, as they would 
do into water, but remain on its surface, and are 
borne onward with the whole mass of the moving 
glacier. The ice is often rent by huge cracks that 
by degrees open into yawning clefts or crevasses. 
Into these deep gashes in the gleaming ice a good 
deal of the earth and stones, let loose by frost or 
otherwise from the sides of the valley, is apt to fall. 
In this way, loose materials reach the bottom of the 
glacier and the solid floor of the valley down which 
it is moving; while at the same time similar rubbish 
tumbles between the edge of the ice and the sides 
of the valley. 

203. Stones and grains of sand, jammed between 
the ice and the rock over which it is moving, are 
made to scour and scratch this rock. They form a 
kind of rough polishing powder, wherewith the glacier 
is continually grinding down the bottom and sides 
of its channel. Were one to creep in below the ice, 
or catch a sight of some part of the side from which 
the ice had retired a little, one would find the sur¬ 
face of rock rubbed smooth, and covered with long 
scratches made by the sharp points of the stones 
and sand. Some of the rounded ice-worn bosses 
of rock are shown in the foreground of the diagram 
(Fig. 13), and one of the scratched stones in Fig. 14. 


98 


PHYSICAL GEOGRAPHY. [circulation 


204. If, then, a glacier is continually grinding 
and polishing the rocks over which it moves, there 
is an evident reason why the river that escapes from 
the end of the ice should always be muddy. The 
bottom of the glacier is stuck over with stones, 
gravel, and sand, which are scraping and wearing 
down the rock underneath. A great deal of fine 
mud is thus produced, which, carried along by water 



Fio. 14.—Loose Stone polished and scratched under Glacier-ice. 


flowing under the glacier, emerges at the far end in 
the discoloured torrents that rush from under the ice. 

205. A glacier is not only busy grinding out a 
bed for itself through the mountains—it bears on its 
back, down the valley, enormous quantities of fallen 
rock, earth, and stones, which have tumbled from 
the cliffs on either side. These materials are called 
moraines (Fig. 13). Blocks of rock as big as a 
house may be thus carried for many miles, and 
dropped where the ice melts. The accompanying 
figure (Fig. 15) represents one of these huge masses 
of stone. Thousands of tons of loose stones and 


OF WATER.] PHYSICAL GEOGRAPHY. 


99 


earth are every year moved on the ice from the far 
snowy mountains down into the valleys to which the 
glaciers reach. 

206. The largest glaciers in the world are those 
of the polar regions. North Greenland, in truth, lies 
buried under one great glacier, which pushes long 
tongues of ice down the valleys and away out to sea. 



Fig. 15.—Erratic Block, brought from the Alps by an ancient Glacier, and 
dropped upon the Jura Mountains. 


When a glacier advances into the sea, portions of it 
break off and float away as icebergs (Fig. 16). So 
enormous are the glaciers in these cold tracts that the 
icebergs derived from them often rise several hundred 
feet above the waves which beat against their sides. 
And yet, as the ice, being frozen fresh water, is 
lighter than the salt water on which it floats, nearly 


100 


PHYSICAL GEOGRAPHY. [circulation 


nine times more of the ice lies under water than the 
portion, large as it is, which appears above. A piece 
of ice, for example, put in a tumbler of water shows 
only its top above the level of the water. Sunk deep 
in the sea, the icebergs float to and fro until they melt 
in mid-ocean, or until, driven into shallow water, they 



Fig. 16.—Iceberg at Sea. 


are stranded, sometimes many hundreds of miles 
away from the glaciers that supplied them. 

207. It has been found out that glaciers once 
abounded all over the northern part of the north 
hemisphere, for the rocks in that region have been 
ground down and scratched, precisely like those by 
the side of modern glaciers; while big blocks of 
rock and piles of loose stones, which the ice had 




or WATEH.] PHYSICAL GEOGRAPHY. 


101 


carried upon its surface, are strewn far and wide over 
the plains. Across the greater part of the British 
Islands, the whole of Northern Europe, Canada, and 
the north-eastern States of America, these and many 
other traces of ancient ice-sheets are to be found. So 
that, in learning about glaciers, we are not merely 
concerned with what takes place in other and distant 
lands, but are gaining knowledge that may be turned 
to good use in enabling us to understand the remote 
history of our own country. 

208. But even in those regions where snow does 
not lie permanently on the ground, it performs im¬ 
portant work in other ways. For example, it covers 
up vegetation, soils, and rocks, and shields them 
from the effects of severe frost. By its rapid thaw it 
allows a large body of water to flow off quickly into 
the rivers, which are thus made to rise suddenly and 
produce disastrous floods (Art. 173). When it col¬ 
lects on the steep slopes of valleys it sometimes slides 
down in great sheets called Avalanches, which, 
gathering force as they descend, sweep earth, stones, 
and trees before them, and carry ruin into the 
meadows below. 


THE SEA. 

I. Grouping of Sea and Land. General 
Features of the Sea. 

209. Since we live on land, and are familiar with 
the various shapes which the surface of the land 


102 


PHYSICAL GEOGRAPHY. 


[the sea. 


assumes,—plains, valleys, hills, mountains, and so on, 
—we are apt to think that the land is the main part 
of the globe. Many who live inland have never seen 
any larger sheet of water than a river or a lake, or 
perhaps a large reservoir. An inhabitant of Great 
Britain, however, cannot travel far in any direction in 
his native country without coming to the edge of the 
land, and finding a vast expanse of water before him. 
He might take ship and sail on that water completely 
round Britain, and would prove in so doing that it 
is an island. 

210. Suppose that instead of sailing round Britain, 
the ship were to be steered straight westward. One 
would have to travel over the water for more than 
two thousand miles before reaching any land again. 
Or, taking a more southerly course, one might sail 
on without seeing any land for months together, 
until the ice-cliffs that border the land round the 
South Pole came in sight. Voyages such as these 
would deeply impress upon the mind what an enor¬ 
mous extent of the surface of the earth is occupied 
by water. 

211. It has been ascertained that in reality the 
water covers about three times more of the earth’s 
surface than the land does. This has been discovered 
by men who have sailed round the world, and have 
crossed it in many directions. 

212. When a school-globe is turned slowly round 
on its axis, we not only see at a glance how much 
larger the surface of water is than the surface of land, 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


103 


but may notice several other interesting features in 
the distribution of land and water. 

213. In the first place, the water is all connected 
together into one great mass, called the sea. One 
might sail from any part of the sea to any other 
part, without having to cross land. The land, on 
the other hand, is much broken up by the way the 
sea runs into it; and some parts are cut off from 
the main mass of land, so as to form islands in the 
sea. One cannot pass from every part of the land to 
every other part without crossing sea. 

214. In the second place, much more land lies on 
the north than on the south side of the equator. 
Turning the globe so as to look straight down on the 
site of London, you will find that most of the land 
comes into sight; whereas, if from the opposite side 
you look straight down on the area of New Zealand, 
you will see most of the sea. London thus stands 
about the centre of the land-hemisphere, midway 
among the countries of the earth. And no doubt 
this central position has not been without its influ¬ 
ence in fostering the progress of British commerce. 

215. In the third place, by the way in which the 
masses of land are placed, parts of the sea are to 
some extent separated from each other. These 
masses of land are called continents, and the wide 
sheets of sea between are termed oceans. The 
surface of the solid part of our globe is uneven, some 
portions rising into broad swellings or ridges, others 
sinking into wide hollows or basins. Now, into 


104 


PHYSICAL GEOGRAPHY. 


[the sea. 


these hollows the sea has been gathered, and only 
those upstanding parts which rise above the level of 
the sea form the land. 

216. In the foregoing parts of this little book 
mention has often been made of the sea. We have 
learnt that much of the moisture of 'the air rises 
from the sea; that the rivers of the land are con¬ 
tinually flowing into the same reservoir of water, 
which is likewise the great basin wherein all the soil 
that is worn from the surface of the land is laid 
down. We must now look a little more closely 
at several of the more important features of the 
sea. 

217. But, first of all, it may be well to try to 
realise the general aspect of the sea. Suppose that, 
standing somewhere by the sea-coast, we see the 
vast expanse of water for the first time. Behind 
us lies the dry land, with its fields and houses and 
roads; but in front, far as the eye can reach, nothing 
except water can be seen, till, along the distant level 
line, the sky seems to rest upon the sea. That line 
where sea and sky meet is called the horizon. 
What a sense of boundless space that wide expanse 
of sea and sky gives us ! As we stand watching it we 
are soon struck by the restlessness of the sea. Even 
on the calmest summer day, a slight ripple or a 
gentle heaving motion may be seen; at other times 
little wavelets curl towards the land, and break in 
long lines upon the beach; but now and then, when 
storms arise, the water is worked up into huge 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


105 


billows which, crested with spray, come in, tossing 
and foaming, to burst upon the shores. 

218. But if the sight of the sea from the land is 
so impressive, far more is that of the boundless 
expanse of mid-ocean. Sailing out of sight of land 
we see nothing but a wide circle of sea and an over¬ 
arching sky. The nearest dry land may be thousands 
of miles away. The water below the vessel may be 
two or three miles deep. Day after day and week 
after week we may sail on, with apparently the same 
circle of ocean all round and the same vault of sky 
overhead. Few or no traces of life may be visible 
either in the air or water. We long for the sight of 
another vessel, and welcome any stray bird or insect, 
as a kind of messenger from the land which we so 
weary to see again. 

219. Unlike the common water of our rivers and 
lakes, the water of the sea is salt. A drop of clear 
spring-water, if allowed to evaporate from a piece of 
glass, leaves no sensible trace behind. The water of 
springs, however (Arts. 130-132), always contains some 
mineral substances dissolved in it, and these, not rising 
in vapour, are left behind when the water evaporates. 
But the quantity of them in a single drop of water 
is so minute that, when the drop dries up, it leaves no 
perceptible speck or film. Take, however, a drop of 
sea-water, and allow it to evaporate. You find a 
little white point or film left behind, and on placing 
that film under a microscope you see it to consist of 
delicate cubical crystals of common or sea-salt, to- 

H 


106 


PHYSICAL GEOGRAPHY. 


[the sea. 


gether with other slender crystals, most of which are 
gypsum. Breathe on the film, and it rapidly becomes 
again a drop of water; the salts have united with 
the condensed moisture and are once more dissolved. 
A similar experiment is made when one bathes in the 
sea and allows the salt water to dry on the body. A 
crust of salt is soon felt to have been left behind 
upon the skin. 

II. Why the Sea is Salt. 

220. Where did the salt in sea-water come from ? 
There is reason to believe that, at a very early stage 
of its history, the earth existed as a mass of intensely 
hot vapour, such as the sun is now, and that, as it 
gradually cooled, the various materials successively 
condensed out of the vapour, so as to build up the 
solid planet, with its envelopes of air and water. The 
atmosphere may thus be regarded as the still gaseous 
residue of the original, far vaster atmosphere, out of 
which the condensation of the planet took place. 
The ocean also may be looked upon as the result 
of later condensations, when the temperature of 
the earth’s surface had sufficiently fallen to allow 
water to remain there. As it condensed and fell 
to earth, the water would carry down with it some 
of the vapours still present in the surrounding warm 
atmosphere. Among these vapours were probably 
salts and other substances still dissolved in sea-water. 

221. But the sea continually receives salt from the 
land. Both underground and on the surface of the 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


107 


land, water is always dissolving out of the rocks 
various mineral substances, of which common salt is 
one (Arts. 130, 138). Hence, as the water of springs 
and of rivers contains salt, a vast quantity of this 
substance must every year be carried into the ocean. 

222. Though the sea gives off again by evapora¬ 
tion as much water as it receives from rain and 
from the rivers of the land (Art. 104), the salt carried 
into it remains behind. When we evaporate salt 
water, though the water disappears, the salt it con¬ 
tains is left behind (Art. 219). So is it on a great 
scale with the sea. While streams are every day 
carrying fresh supplies of salt into the sea, millions 
of tons of water are every day also passing from the 
ocean into vapour in the atmosphere. The water is 
fresh as it rises into vapour, but is slightly saline as 
it flows back from the land into the sea. The waters 
of the sea must, consequently, be getting salter by 
degrees, though the process, no doubt, is an extremely 
slow one. 

223. Although ever since rivers first flowed into 
it the sea has been gradually growing in saltness, it is 
even now by no means as salt as the water of some 
inland seas which have no outlet to the main ocean. 
In the Atlantic Ocean, for example, the total quantity 
of the different salts amounts only to about three 
and a half parts in every hundred parts of water. 
But in the Dead Sea, which is extremely salt, the 
proportion is as much as twenty-four parts in the 
hundred of water. 


108 


PHYSICAL GEOGRAPHY. 


[the sea. 


III. The Motions of the Sea. 

224. Watching by the shore of the open sea, we 
perceive that no matter what may be the state of the 
weather, the surface of the water is never perfectly 
still. Moreover we soon observe that the actual edge 
of the sea does not remain at exactly the same limit. 
At one hour of the day it reaches to the upper part 
of the sloping beach; some six hours afterwards it 
has retired to the lower part. It falls and rises, day 
after day, and year after year, with so much regularity 
that its motion can be predicted long beforehand. To 
this ebb and flow of the sea the name of tides has 
been given. 

225. An empty bottle, corked up and thrown into 
the sea, will float; but will not remain long where it 
first fell. It will begin to move away, and may 
travel for a long distance until thrown upon some 
shore again. Bottles cast upon mid-ocean have been 
known to be carried in this way for many hundreds 
of miles. This surface-drift of the sea-water corre¬ 
sponds generally with the direction in which the 
prevalent winds blow. 

226. But it is not merely the surface-water which 
moves. Icebergs, for example,—of each of which, large 
as it may seem, there are about nine times more 
below water than above,—are sometimes seen sailing 
on, even right in the face of a strong wind. This 
shows them to be moving, not with the wind, but 
with a strong under-current in the sea. In short, the 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


109 


sea is found to be traversed by many currents, like 
great rivers, some flowing from cold to warm regions, 
and others from warm to cold. 

227. Here, then, are four facts about the sea:— 
1st, it has a restless surface, disturbed by ripples and 
waves; 2d, it is constantly heaving with the ebb 
and flow of the tides; 3d, its surface-waters drift 
with the wind; and 4th, it possesses deep and wide 
currents. 

228. For the present, it will be enough to attend 
to the first of these facts—the waves of the sea. 
Here again we may illustrate by familiar objects what 
goes on upon so vast a scale in nature. Take a basin 
or a long trough of water, and blow upon the water 
at one edge. Its surface is at once thrown into ripples, 
which, as you will observe, start from the place where 
your breath first hits the water, and roll onward until 
they break in little wavelets upon the opposite margin 
of the basin. 

229. Ordinary waves are disturbances of the smooth¬ 
ness of the sea, due to disturbances of the air. Wind 
acts upon the water of the sea as your breath does 
on that of the basin. Striking the surface, it throws 
the water into ripples or undulations, and in con¬ 
tinuing to blow along the surface it gives these ad¬ 
ditional force, until, driven onwards by a furious 
gale, they grow into huge billows. 

230. When waves roll in on the land, they break 
one after another upon the shore, as your ripples 
break upon the side of the basin. And they continue 


110 


PHYSICAL GEOGRAPHY. 


[THE SEA. 


to roll in after the wind has fallen, in the same way 
that ripples will still undulate in the basin for a 
little after you have ceased to blow. The surface of 
the sea, like that of water generally, is very sensitive. 
If thrown into pulsations, it does not become motion¬ 
less the moment the cause of disturbance has passed 
away, but continues moving, in a gradually lessening 
degree, until it comes to rest. Moreover, the undula¬ 
tions may travel far away from the place where the 
storm blew that caused them. They roll ashore and 
break there in waves. This heaving of the sea after 
a storm is known as Groundswell. 

231. The restlessness of the surface of the sea 
becomes in this way a reflection of the restlessness of 
the air. It is the constant moving to and fro of cur¬ 
rents of air, either gentle or violent, which dimples 
the sea with ripples or roughens it with waves. When 
the air for a time is calm above, the sea sleeps peace¬ 
fully below; when the sky darkens, and a tempest 
bursts forth, the sea is lashed into waves, which 
roll in and break with enormous force upon the 
land. 

232. Everyone who has ever lived upon a coast¬ 
line must have heard, or may even have seen, some¬ 
thing of the destruction worked by the waves of 
the sea. Every year piers and sea-walls are broken 
down, pieces of the coast are washed away, and 
the shores are strewn with the wreck of ships. So 
that, besides all the waste which the surface of the 
land undergoes from rain, frost, and streams, there 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


Ill 


is another form of destruction going on along the 
sea-margin. 

233. On rocky shores, the different stages in the 
eating away of the land by the sea can sometimes 
be strikingly seen. Above the beach, perhaps, rises 
a cliff, sorely battered about its base by the ceaseless 
grinding of the waves. Here and there, a cavern has 



Fig. 17.—Coast-line worn by the Sea. 


been drilled in the solid wall, or a tunnel has been 
driven through some projecting headland. Not far 
off we may note a tall buttress of rock, once a part 
of the main cliff, but now separated from it by the 
falling in and removal of the connecting archway. 
And then, farther from the cliff, isolated, half-tide 
rocks rise to show where still older detached buttresses 
stood ; while away out in the sea the dash of breakers 











112 


PHYSICAL GEOGRAPHY. 


[the sea. 


marks the site of some sunken reef,—the relics of a 
still more ancient coast-line. On such a shore the 
whole process whereby the sea eats into the land 
seems to be laid open to our eyes. 

234. On some parts of the coast-line of the east of 
England, where the rock is easily worn away, the sea 
advances on the land at a rate of two or three 
feet every year. Towns and villages which existed 
a few centuries ago have one by one disappeared, 
and their sites are now a long way out under the 
restless waters of the North Sea. On the west side 
of Britain, however, along the coast of Ireland and 
Scotland, the rocks being usually hard and resisting, 
the rate of waste has been comparatively small 

235. Those who have the good fortune to live at 
or to visit a rocky coast-line should endeavour to 
ascertain what means the sea takes to waste the 
land. Let them take their stand on some sandy or 
gravelly part of the beach, over which the waves are 
breaking, and keep their eye on the water when it 
runs back after a wave has burst. The pebbles of 
gravel and grains of sand may be seen hurrying down 
the slope with the water. If the gravel happens to 
be coarse, it makes a harsh grinding roar as its stones 
rub against each other—a noise which, in storms, is 
sometimes loud enough to be heard miles away. As 
the next wave comes curling along, it will be ob¬ 
served that the sand and gravel, after slackening 
their downward pace, are caught up by the bottom 
of the advancing wave and dragged up the beach 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


113 


again, only to be hurried down once more, as the 
water retires to allow another wave to do the same 
work. 

236. By this continual up and down movement of 
the water, the sand and stones on the beach are kept 
grinding against each other, as in a mill. Con¬ 
sequently, they are gradually ground smooth and 
worn away. The stones become smaller, until they 
pass into mere sand, and the sand, growing finer, is 
swept away out to sea and laid down at the bottom. 

237. But not only the loose materials on the 
shore suffer in this way an incessant wear and tear: 
the solid rocks underneath, wherever they come to 
the surface, are ground down in the same process. 
When the waves dash against a cliff, they hurl the 
loose stones forward, and batter the rocks with them. 
Here and there, in some softer part, as in some 
crevice of the cliff, these stones gather together, and 
when the sea runs high, they are kept whirling and 
grinding at the base of the cliff, till, in the end, a 
cave is actually bored by the sea in the solid rock, 
very much in the same way as holes are bored by a 
river in the bed of its channel (Art. 179). The 
stones, of course, are ground to sand in the process, 
but their place is supplied by others swept up by 
the waves. If you enter one of these sea-caves when 
the water is low, you will see how smoothed and 
polished its sides and roof are, and how well rounded 
and worn are the stones lying on its floor. 


114 


PHYSICAL GEOGRAPHY. 


[the sea. 


IV. The Bottom of the Sea. 

238. So far as we know, the bottom of the sea is 
somewhat like parts of the surface of the land. It has 
heights and hollows, vast plains, lines of valleys, and 
ranges of hills. Though these cannot be seen by the, 
eye, their existence and distribution are ascertained 
by means of a long line with a lead-weight or a dredge 
tied to the end of it. In this way we discover the 
depth of the water, and what is the nature of the 
bottom, whether rock or gravel, sand, mud, or shells. 
This measuring of the depths of the sea is called 
Sounding. 

239. Soundings have been made over many parts 
of the sea, and much is now known about its depth 
and the nature of its bottom. The Atlantic Ocean, 
which has been particularly explored, has probably an 
average depth in its opener parts of from two to 
three and a half miles. Here and there are deep 
submarine hollows that sink below the average 
level. About 100 miles from the island of St. 
Thomas, for example, a sounding was obtained of 
nearly four miles and a half. If Mont Blanc, which 
is the highest mountain in Europe, reaching a height 
of 15,744 feet above the sea, could be set down in 
the deepest part of the Atlantic, it would not only 
sink out of sight, but its top would actually be nearly 
a mile and a half below the surface. 

240. The average depth of the sea is probably not 
much below three miles. But even in the midst of the 


THE SEA.] 


PHYSICAL GEOGKAPHY. 


115 


oceans some parts of the bottom rise up to the sur¬ 
face and form islands. As a rule, water deepens 
towards mid - ocean, and shallows towards land. 
Hence those parts of the sea which run in among 
islands and promontories are, for the most part, com¬ 
paratively shallow. To the west of the island of 
Great Britain stretches the wide and deep Atlantic 
Ocean; to the east lies the much smaller and shal¬ 
lower North Sea, which never deepens much even 
over its middle parts, where there is nowhere a depth 
of so much as 400 feet. Some notion may he formed 
of the shallowness of the sea between England and 
France, from the statement that if St. Paul’s Cathe¬ 
dral could be lifted from London, and set down in 
the middle of the Strait of Dover, more than a half 
of the building would he out of the water. 

241. Not only have successful soundings been 
made of the deepest abysses of the sea, but by means 
of the dredge it has been possible to bring up 
bucketfuls of whatever may be lying on the sea¬ 
floor, even at the profoundest depths. In this way, 
during the last few years a great deal of additional 
knowledge has been gathered as to the nature of the 
sea-floor, and the kind of plants and animals which 
live there. Over wide spaces on the floor of the great 
ocean there is abundant animal life, such as shells, 
corals, star-fishes, and still more humble creatures. 

242. In earlier parts of this book we have traced 
some of the changes which from day to day take 
place upon the surface of the land. Let us now try 


116 


PHYSICAL GEOGRAPHY. 


[the sea. 


to realise some of those which must go on upon the 
floor of the sea. We cannot, indeed, examine the 
sea-bottom with anything like the same minuteness as 
the surface of the land. Yet a great deal may be 
learnt regarding it. 

243. Putting together some of the facts detailed 
in the foregoing Lessons, we may without difficulty 
understand some of the most important changes 
which are in progress on the floor of the sea. We 
have learnt what a prodigious amount of wasted rock 
is every year removed from the surface of the land 
and carried into the sea by streams (Art. 186). From 
the time when it was loosened from the sides of 
the mountains, hills, or valleys, this decomposed 
material has been seeking a lower level. On reach¬ 
ing the hollows of the sea-bottom it cannot descend 
any farther, but must necessarily accumulate there. 

244. It is evident, then, that between the floor of 
the sea and the surface of the land there must be 
this great difference: that whereas the land, where- 
ever exposed to the air, rain, frost, and the general 
decay that affects the surface (Arts. 133-158), is 
undergoing a continual destruction, from mountain- 
crest to sea-shore ; the sea-bottom, on the other hand, 
is constantly receiving deposits of fresh materials. 
The one is increased in proportion as the other is 
diminished. So that even without knowing anything 
regarding what men have found out by means of 
deep soundings, we could confidently assert that 
every year there must be vast quantities of gravel, 


THE SEA.] 


PHYSICAL GEOGRAPHY. 


117 


sand, and mud laid down upon the floor of the sea, 
because we know that these materials are worn away 
from the land. 

245. Again, the restless agitation of the sea is 
caused by movements of the air, and the destruction 
which the sea can effect on the land is largely due 
to the action of waves raised by wind. But this 
action must be merely a surface one, and can only 
affect coast-lines and shallow parts of the sea-floor. 
The influence of the waves cannot reach to the bottom 
of the deep sea. Consequently that bottom lies 
beyond the reach of the various kinds of destruction 
which so alter the face of the land. The materials 
derived from the waste of the land can lie on the 
sea-floor without further disturbance than they may 
suffer from the quiet flow of such ocean-currents as 
touch the bottom. 

246. In what way, then, are the gravel, sand, and 
mud disposed of when they reach the sea ? As these 
materials are all brought from the land, they accumu¬ 
late on those parts of the sea-floor which border the 
land, rather than at a distance. Banks of sand and 
gravel may be expected to occur in shallow seas and 
near land, but not in the middle of the ocean. 

247. We may form some notion, on a small scale, 
as to how the materials are arranged on the sea- 
bottom, by examining the channel of a river in a 
season of drought. At one place, where the current 
has been strong, there may be a bank of gravel; at 
another place, where feebler currents of the river 


118 


PHYSICAL GEOGRAPHY. 


[the sea. 


have met, we find, perhaps, a ridge of sand which 
they have heaped up; while in those places where 
the flow of the stream has been still more gentle, the 
channel may be covered with a layer of fine silt or mud. 

248. A muddy river may be made to deposit its 
mud if it overflows its banks so far as to spread 
across flat land, for in so doing it has its flow 
checked (Art. 182). The more powerful a current 
of water, the larger are the stones it can move along. 
Hence, coarse gravel is not likely to be found over 
the bottom of the sea, except near the land, where 
the waves can sweep it out into the path of strong 
sea-currents, or in the track of icebergs, which some¬ 
times bear earth and stones on their surface and drop 
them on the sea-floor as the ice melts. Sand will 
generally be carried farther out than gravel, and 
will be laid down in great sheets, or in banks. The 
finer mud and silt, though occasionally borne by 
currents for two hundred miles or more, probably, 
as a rule, settle on the sea-bottom before they have 
been carried more than forty or fifty miles from land. 

249. The sand, mud, and gravel, worn from the 
land, are thus spread out in vast sheets and banks 
over that part of the bottom of the sea that lies near 
the land. But over by far the largest part of the 
sea-floor there can be little or no deposit of even the 
finest sediment borne from the land. Bed and gray 
clay, composed of volcanic detritus and possibly de¬ 
rived mainly from submarine volcanoes, covers vast 
spaces of the floor of mid-ocean. 


THE SEA. ] 


PHYSICAL GEOGRAPHY. 


119 


250. But the sea is full of life, both of plants and 
animals. These organisms die, and their remains 
are necessarily mixed up with the different materials 
laid down upon the sea-floor. So that, besides sand, 
clay, and mud, great numbers of shells, corals, and the 
harder parts of other sea-creatures, must be buried 
there, as generation after generation lives and dies. 

251. It often happens that on parts of the sea-bed 
the remains of some of these animals are so abundant 
as to form of themselves*wide-spread accumulations. 
Oysters, for example, grow thickly together; and 
their shells, mingled with those of other similar 
creatures, form what are called sheU-banks. In 
the Pacific and the Indian oceans a little animal, 
called the coral-polyp, secretes a hard limy skeleton 
from sea-water ; and as millions of these polyps grow 
together, they form great Coral-reefs, which are solid 
limestone, sometimes, as in the Great Barrier Beef of 
Australia, hundreds of feet thick and a thousand miles 



Fig. 18.—Island formed by the Growth of Coral. 


long. It is by means of the growth of these animals 


120 


PHYSICAL GEOGRAPHY. 


[the sea. 


that those wonderful rings of coral-rock or Coral- 
islands (Fig. 18) are formed in the middle of the 
ocean. Again, a great part of the bed of the Atlantic 
Ocean is covered with fine ooze, which on examina¬ 
tion is found to consist almost wholly of the remains 
of very minute animals called Foraminifera (Fig. 19). 

252. Over the bottom of the sea, therefore, ex¬ 
tensive and probably deep accumulations of sand and 
mud, mingled with the remains of plants and animals, 
have in the course of ages been formed, and are still 



Fig. 19.— Ooze from floor of Atlantic Ocean, consisting chiefly of 
Foraminifera; magnified 25 times. 


continually being increased by fresh deposits. Were 
the ocean-floor to be raised up above the sea-level, 
and were its sand and mud to become as dry and 
hard as any rock among the hills, it would never¬ 
theless be possible to say with certainty that these 
materials had once been the bed of the sea, because 
they would be found to enclose the shells and other 
remains of creatures that could only have lived in 
the sea. 

253. You will afterwards learn when you come to 
the science of Geology that this raising of the sea- 



THE SEA.] 


PHYSICAL GEOGRAPHY. 


121 


bottom has often taken place in ancient times. You 
will find most of the rocks of our hills and valleys to 
have been originally laid down in the sea, where they 
were formed out of sand and mud dropped on the sea¬ 
floor, just as sand and mud are carried out to sea and 
laid down there now. And in these rocks, not merely 
near the shore, but far inland, in quarries or ravines, 
on the sides and even on the tops of hills, you will 
be able to pick out the skeletons and fragments of 
the various sea-creatures that lived in the old seas. 

254. Since the bottom of the sea forms the great 
receptacle into which the mouldered remains of the 
surface of the land are continually carried, it is plain 
that if the present state of things were to go on 
without interruption, in the end the whole of the solid 
land would be worn away, and its remains would be 
spread out on the sea-floor, leaving one vast ocean to 
roll round the globe. 

255. But there is in nature another force which 
here comes into play to retard the destruction of the 
land. In the remaining Lessons we shall inquire 
what this force is, and how it works. 


THE INSIDE OF THE EARTH. 

256. The foregoing pages have described the sur¬ 
face of the earth, and what goes on there. Let us 
now consider for a little what can be learnt regard¬ 
ing the inside of the earth. It may seem, at first, 
hardly possible that man should ever know anything 
I 


122 


PHYSICAL GEOGRAPHY. 


[inside of 


about the earth’s interior. Think what a huge ball 
this globe of ours is, and how, in living and moving 
over its surface, we are merely like flies walking over 
a great hill. All that can be seen from the top of 
the highest mountain to the bottom of the deepest 
mine is not more, in comparison with the size of the 
whole earth, than the mere varnish on the outside 
of a school-globe. 

257. And yet a good deal may be learnt as to 
what takes place within the earth. Here and there, 
in different countries, there are places where com¬ 
munication exists between the interior and the sur¬ 
face ; and it is from such places that much of our 
information on this subject is derived. Volcanoes 
or Burning-mountains (Fig. 20) are among the 
most important of these channels of communication. 

258. Suppose you were to visit one of these vol¬ 
canoes just before what is called an “eruption.” 
From the distance it appears as a conical mountain 
with its top cut off. From this truncated summit a 
white cloud rises; but not quite such a cloud as 
may be seen on an ordinary hill-top. For after 
watching it a little time, you would notice that it 
rises out of the top of the mountain, even when the 
sky is cloudless. Ascending from the vegetation of the 
lower grounds, you would find that the slopes con¬ 
sist partly of loose stones and ashes, partly of rough 
black sheets of rock, like the slags of an iron furnace. 
Nearer the top the ground feels hot, and puffs of 
steam, together with stifling vapours, come out of it 


THE EARTH.] PHYSICAL GEOGRAPHY. 


123 


here and there. At last when the summit is reached, 
what seemed from below to be a level top is seen to 
be in reality a great basin, with steep walls descend¬ 
ing into the depths of the mountain. Screening 
your face as well as possible from the hot gases 
which would almost choke you, you might creep to 
the edge of this basin and look down into it. Far 



Fig. 20.—View of a Volcano. Mount Vesuvius as it appears at the 
present time when viewed from the south. 


below, at the base of the rough red and yellow cliffs 
which form its sides, lies a pool of some liquid glow¬ 
ing with a white heat, though covered for the most 
part with a black crust like that seen on the outside 
of the mountain during the ascent. From this fiery 
pool jets of the red-hot liquid are jerked out every 
now and then, and harden into stone as they are 
cooled in the air. Showers of stones and dust are 














124 


PHYSICAL GEOGRAPHY. 


[inside of 


shot forth and fall back again into the caldron or 
down the outside of the mountain. Clouds of steam 
ascend from the same source to form the uprising 
cloud which is seen from a great distance, hanging 
over the mountain-top. 

259. The caldron-shaped hollow on the summit of 
the mountain is called the Crater. The intensely- 
heated liquid in the sputtering boiling pool at its 
bottom is melted rock or Lava. The fragmentary- 
materials—ashes, dust, cinders, and stones—are torn 
from liquid lava or from the hardened sides and 
bottom of the crater by the violence of the explosions 
with which the gases and steam escape. 

260. The hot air and steam, and the melted mass 
at the bottom of the crater, show that there must be 
some source of intense heat underneath. And as the 
heat has been coming out for hundreds or even thou¬ 
sands of years, it must exist there in great abundance. 

261. But it is when the volcano appears in active 
eruption that the power of this underground heat 
shows itself most markedly. For a day or two 
beforehand the ground around the mountain trembles. 
At length, in a series of violent explosions, the heart 
of the volcano is torn open, and perhaps its upper 
part is blown into the air. Huge clouds of steam 
roll away up into the air, mingled with fine dust and 
red-hot stones. The heavier stones fall back again 
into the crater, or on the outer slopes of the moun¬ 
tain, but the finer ashes come out in such quantity 
as sometimes to darken the sky for many miles 


THE EARTH.] PHYSICAL GEOGRAPHY. 


125 


round, and to settle down over the surrounding 
country as a thick covering. Streams of molten 
lava run down the outside of the mountain, and 
descend even to the gardens and houses at the base, 
burning up or overflowing whatever lies in their path. 
This state of matters continues for days or weeks, 
until the volcano exhausts itself, and then a time 
of comparative quiet comes when only steam, hot 
vapours, and gases are given off. 

262. About 1800 years ago there was a mountain 



Fio. 21.—Vesuvius as it appeared before Pompeii was destroyed. 


near Naples shaped like a volcano, and with a large 
crater covered with brushwood (Fig. 21). No one 
had ever seen any steam, or ashes, or lava come from 
it, and the people did not imagine it to be a volcano, 
like some other mountains in that part of Europe. 
They had built villages and towns around its base, 
and their district, from its beauty and soft climate, 










126 


PHYSICAL GEOGRAPHY. 


[inside op 


used to attract wealthy Bomans to build villas there. 
But at last, after hardly any warning, the whole of 
the higher part of the mountain was blown into the 
air with terrific explosions. Such showers of fine 
ashes fell for miles around that the sky was as dark 
as midnight. Day and night, the ashes and stones 
descended on the surrounding country; many of the 
inhabitants were killed, either by stones falling on 
them, or from suffocation by the dust. When at last 
the eruption ceased, the district, which had before 
drawn visitors from all parts of the Old World, 
was found to be a mere desert of gray dust and 
stones. Towns and villages, vineyards and gardens, 
were all buried. Of the towns, the two most noted, 
called Herculaneum and Pompeii, so completely dis¬ 
appeared that, although important places at the 
time, their very sites were forgotten, and only by 
accident, after the lapse of some fifteen hundred 
years, were they discovered. Excavations have since 
that time been carried on, the hardened volcanic 
accumulations have been removed from the two old 
towns, and one can now walk through the streets of 
Pompeii again, with their roofless dwelling-houses 
and shops, theatres and temples, and mark on the 
causeway the deep ruts worn by the carriage wheels 
of the Pompeians eighteen centuries ago. Beyond 
the walls of the now silent city rises Mount Vesuvius, 
with its smoking crater, covering one-half of the old 
mountain which was blown up when Pompeii dis¬ 
appeared (see Fig. 20). 


THE EARTH.] PHYSICAL GEOGRAPHY. 


127 


263. Volcanoes, then, mark the position of some 
of the holes or orifices, whereby heated materials from 
the inside of the earth are thrown up to the surface. 
They occur in all quarters of the globe. In Europe, 
besides Mount Vesuvius, which has been more or less 
active since its great eruption in the first century, 
Etna, Stromboli, Santorin, and other smaller vol¬ 
canoes, occur in the basin of the Mediterranean; 
while far to the north-west, active volcanoes rise amid 
the snows and glaciers of Iceland. In South America 
a chain of huge volcanoes stretches down the range of 
the Andes, that rise near the western margin of the 
continent. In Asia, volcanoes are thickly grouped 
together in Java and the surrounding islands, where 
in August 1883 there occurred one of the most stu¬ 
pendous volcanic eruptions of recent times. From 
that district a line of active volcanoes stretches through 
Japan and the Aleutian Isles to the extremity of 
North America. Tracing this distribution upon the 
map, we observe that the Pacific Ocean is girdled 
round with volcanoes. 

264. Since these openings into the interior of the 
earth are so numerous over the surface, we may con¬ 
clude that the interior is intensely hot. But other 
proofs of this internal heat may be gathered. In many 
countries hot springs rise to the surface. In some 
volcanic districts hot water and steam gush out at 
intervals with great force, and for a height of a 
hundred feet or more, into- the air. Even in England, 
which is a long way from any active volcano, the 


128 


PHYSICAL GEOGRAPHY. 


[inside of 


water of the wells of Bath is quite warm (120° Fahr.) 
It is known, too, that in all countries the heat 
increases as we descend into the earth. The deeper 
a mine the warmer are the rocks and air at its 
bottom. If the heat continues to increase in the 
same proportion, the rocks must be red Lot at no 
great distance beneath us. We must conclude, then, 
that this globe on which we live has a comparatively 
thin, cool outer shell or crust, within which the 
interior is intensely hot. 

265. The explosions of a volcano shake the ground, 
sometimes with great violence. But the solid earth 
is affected by movements even remote from any 
volcano. Very delicate instruments have revealed 
that though the ground beneath us seems to be 
perfectly steady, it is continually affected by slight 
tremors. When the movement becomes strong 
enough to be quite perceptible it is called an earth¬ 
quake, which may vary from a feeble, hardly sensible 
trembling of the ground up to a violent concussion, 
whereby the ground is convulsed and even rent open, 
trees, rocks, and buildings are thrown down, and 
sometimes thousands of people are killed. Earth¬ 
quakes are more particularly frequent and destructive 
in regions where active volcanoes exist. 

266. Though earthquakes may destroy much life 
and property, they do not permanently alter the 
face of the globe so much as another kind of 
earth-movement of a much slower and less startling 
nature. Some parts of the land are slowly rising. 


THE EARTH.] PHYSICAL GEOGRAPHY. 


129 


When this upheaval takes place in maritime tracts, 
rocks that used always to he covered by the tides 
come to lie wholly beyond their limits; while others, 
once never to be seen at all, begin one by one to 
show their heads above water. On the other hand, 
some regions are slowly sinking; piers, sea-walls, and 
other old landmarks on the beach, are one after 
another enveloped by the sea as it encroaches farther 
and higher on the land. 

267. Even at the present day, therefore, we know 
that one result of the movements of the outer part 
or crust of the earth is to raise some regions above 
the level of the sea, and to increase the height of 
others that are already dry land. Reflecting on this 
process, we soon perceive that it must be by such 
elevations that dry land continues upon the face of 
the earth. If rain and frost, rivers, glaciers, and the 
sea, were continually and without check to wear 
down the surface of the land, that surface would 
necessarily in the end disappear, and indeed must 
have disappeared long ago. But, on the one hand, 
owing to the pushing out of some parts of the earth’s 
surface from within, portions of the land are raised 
to a higher level, while parts of the bed of the sea 
are actually upheaved so as to form land. On the 
other hand, certain tracts, more particularly of the 
ocean-floor, sink inward; the ocean-basins are thus 
deepened, and in some measure the level of the sea 
is thereby lowered. 

268. This kind of oscillation has happened many 


130 


PHYSICAL GEOGRAPHY. [conclusion. 


times in all quarters of the globe. As already men¬ 
tioned (Art. 253), most of our hills and valleys are 
formed of rocks which were originally laid down on 
the bottom of the sea, and have been subsequently 
raised into land. In almost every country proofs 
may be found that the land has repeatedly been sub¬ 
merged and re-elevated. 

CONCLUSION. 

269. In conclusion, let us sum up the leading 
features of the foregoing Lessons. 

The Earth is the scene of continual movement and 
change. The atmosphere that encircles it is ever in 
motion, diffusing heat, light, and vapour. From the 
sea and from the waters of the land, vapour is con¬ 
stantly passing into the air, whence, condensed into 
dew, clouds, rain, hail, and snow, it descends again to 
the earth. All over the surface of the land the water 
that falls from the sky courses seawards in brooks and 
rivers, bearing into the great deep the materials which 
are worn away from the land. Water is thus cease¬ 
lessly circulating between the air, the land, and the 
sea. The sea, too, is never at rest. Its waves gnaw 
the edges of the land, and its currents sweep round the 
globe. Into its depths the spoils of the land are 
borne, there to gather into rocks, out of which new 
islands and continents will eventually be formed 
Lastly, while the outer layers of the earth are cool, 
the interior must be intensely hot. This internal 


conclusion.] PHYSICAL GEOGRAPHY. 


131 


heat manifests itself in a striking way at the surface 
in volcanoes and boiling springs. From time to 
time also the solid earth is convulsed with earth¬ 
quakes. There are movements of a more tranquil 
kind whereby some tracts are upraised and others 
are depressed. Thus, while old land is submerged 
beneath the sea, new tracts are upheaved, to be 
clothed with vegetation and peopled with animals, 
and to form a fitting abode for man himself. 

270. This world is not a living being, like a plant 
or an animal, and yet there is evidently a sense in 
which we may speak of it as endowed with life. 
The circulation of air and water, the interchange of 
sea and land,—in short, the system of endless and 
continual movement by which the face of the globe 
is day by day altered and renewed,—may well be 
called the Life of the Earth. 


132 


PHYSICAL GEOGRAPHY. [questions. 


QUESTIONS. 

THE SHAPE OF THE EARTH, p. 9. 

1. What is the first impression we have of the shape of the 
Earth ? 

2. How could you show, in the interior of a level country, that 
the apparent plain is really part of the surface of a globe ? 

3. Prove the same conclusion from what may be seen on the 
sea-coast. 

4. How has the shape of the Earth been tested by “ circum¬ 
navigators ? ” 

5. Show how the gentle curvature indicates the size of the 
Globe. 

6. How long would a railway train moving at a rate of thirty 
miles an hour take to go round the Earth ? 

7. What is meant by Science ? (p. 12.) 

DAY AND NIGHT, p. 15. 

1. Whence does the Earth receive its surface heat and light ? 

2. What was the ancient belief as to the relative positions of 
the Earth, sun, moon, and stars ? 

3. Are there any traces of this early belief still to be found 
in our everyday speech ? 

4. What is the real relation of the Sun to the Earth ? 

5. The succession of Day and Night appears as if it were due 
to the movement of the sun across the sky ; illustrate how it is 
really caused by the motion of the earth ? 

6. What is meant by the terms axis of rotation , north pole 
and south pole t 


QUESTIONS.] PHYSICAL GEOGRAPHY. 


133 


7. In what direction is the Earth rotating ? How is this 
indicated by day and at night respectively ? 

8. What is the Earth's motion of revolution ? 

9. In what time does the Earth perform a complete revolution ? 

10. Show how the movements of the Earth determine our 
divisions of time. 

THE AIR. 

I. What the Air is made of, p. 19. 

1. What is meant by the term Atmosphere l 

2. Of what materials is the Air mainly composed ? 

3. Besides the two chief gases, name some other substances 
always present in the Air. 

4. How may the presence of visible particles in the Air be 
shown ? 

5. What is Water - vapour ? [See art. 66.] Show by any 
familiar example how it may be invisibly dissolved in the air 
[See art. 64.] 

6. In what proportion does Carbonic Acid Gas occur in the 
air ? 

7. Show how important this material is in relation to the 
growth of Plants and Animals. 

II. The Warming and Cooling of the Air, p. 22. 

1. In what ways are we made sensible of the presence of the 
Air? 

2. Why do we feel cold when we pass from a warm room into 
the outer air in winter ? 

3. How are changes of Temperature measured ? 

4. What is meant by Radiation ? 

5. The sun is always radiating heat to the Earth ; why then 
should there be alternations of heat and cold in the air ? 

6. Does the Atmosphere allow the whole of the sun’s heat- 
rays to pass through it to the surface of the Earth ? 

7. Why is the sun’s heat less felt in the morning and in the 
evening than at noon ? 

8. Why is Night so much colder than Day ? 

9. Why is Summer warmer than Winter ^ * 


134 PHYSICAL GEOGRAPHY. [questions. 

10. Why is it that cloudy days are not always or necessarily 
cold ? 

11. Since the Air absorbs only part of the heat of the sun 
which passes through it to the Earth’s surface, how is it chiefly 
warmed and how cooled ? 

12. What prevents excessive loss of heat at night by radia¬ 
tion ? 

13. Why are the nights often felt to be so cold in hot and 
desert climates ? 

14. Why are cloudy nights usually warmer than clear ones ? 

III. The Vapour in the Air. Evaporation and Condensa¬ 
tion, p. 28. 

1. Explain why a film of mist appears on a cold glass when 
brought into a warm room, and on the inside of window- 
panes. 

2. What is the meaning of the words condensed and condensa¬ 
tion ? 

3. How does the capacity of the Air to retain water-vapour 
vary ? 

4. Why does a film of mist appear upon a mirror or other 
cold surface when it is breathed on, and what is the explanation 
of the cloud which issues from one’s mouth with every breath 
in cold weather ? 

5. What is the Dew-point ? 

6. How is the vapour of water brought into the Air ? Show 
how this may be experimentally illustrated. 

7. Explain the process of Evaporation. 

8. At what times is Evaporation most and least vigorous ? 

9. Why do not wet clothes dry on a damp day ? 

10. Explain the cause of the chill that is felt when a drop 
of water is evaporated on the back of the hand. 

11. What is estimated to be the amount of water-vapour 
annually condensed upon the Earth’s surface ? 

IV. Dew, Mist, Clouds, p. 33. 

1. Give some examples of the condensation of Vapour. 

2. Explain the formation of Dew. 


QUESTIONS.] PHYSICAL GEOGRAPHY. 


135 


3. Show how Mists are formed upon mountains. 

4. Explain the origin of the fog often seen rising after sunset 
from the surface of a river. 

5. Explain the formation of Clouds. 

V. Rain and Snow, p. 37. 

1. In what ways do Clouds disappear from the sky? 

2. Explain the formation and fall of Rain. 

3. In what different conditions does the substance called 
Water exist ? 

4. What is Ice ? 

5. What is meant by the Freezing-point ? 

6. Describe a Snow-flake. 

7. What is the effect of elevation above the earth’s surface 
upon Temperature ? 

8. What are Hail and Sleet ? 

VI. The Movements of the Air, p. 40. 

1. What evidence have we that the Air is always in motion ? 

2. Whether is warm or cold air the heavier, and why ? 

3. How does this difference in weight affect the movements of 
the Air ? 

4. Show how the effect of heat in causing motion of the Air 
may be illustrated by a red-hot poker. 

5. On what principle are open fire-places constructed ? 

6. Does all the heat of an open fire-place go to warm the room ? 

7. What are the different effects of an open fire-place and a 
close stove upon the ventilation of a room ? 

8. Show how it may be proved that the heat of sunshine is 
not due to warmth of the Air ? 

9. Explain how the heating of the Earth’s surface causes Wind ? 

10. Describe the Land- and Sea-breezes, and explain the 
cause of them. 

11. How are the movements of the Air affected by its water 
vapour ? 

12. What is meant by the Pressure of the Atmosphere ? 

13. Explain the use of the Barometer ? 

14. What is the cause of Hurricanes ? 


136 


PHYSICAL GEOGRAPHY. [questions. 


15. Where are the chief areas of high and low Atmospheric 
Pressure, and how do they affect the greater movements of the 
Atmosphere ? 

16. Why are there copious Rains in the Equatorial regions ? 

17. Explain the origin of the Trade Winds. 

18. What is the general rule or law that governs all move¬ 
ments of the Atmosphere ? 

THE CIRCULATION OF WATER ON THE LAND, p. 46. 

1. Whence does the Atmosphere obtain its Vapour ? 

2. Into what visible forms is the Vapour condensed ? 

3. Into what forms is the moisture of Clouds resolved ? 

4. Of what uses is the Circulation of Water between the 
Atmosphere and the Earth ? 

I. What becomes of the Rain, p. 47. 

1. Why do not seas, lakes, and rivers become visibly less, 
seeing that they lose so much water by evaporation ? 

2. What part does the Sea play in supplying the air with 
moisture ? 

3. What becomes of that part of the Rain which falls into the 
Sea? 

4. How much Rain is estimated to fall annually upon the 
British Isles ? 

5. What is the annual Rainfall in some parts of India ? 

6. What becomes of runnels of rain-water ? 

7. What proportion of the Rainfall is discharged into the sea 
by rivers ? What becomes of the rest ? 

8. How may it be shown that a considerable quantity of rain 
sinks into the ground, and yet that this quantity is not per¬ 
manently removed from the circulation ? 

9. How is the rain disposed of which falls upon the surface 
of the Land ? 

II. How Springs are formed, p. 61. 

1. How do sand and clay differ from each other in regard to 
the passage of water through them ? 


questions.] PHYSICAL GEOGRAPHY. 


137 


2. How does this difference affect the kinds of Soil ? 

3. What inference as to the movements of underground 
water may be drawn from the fact that water gathers in any 
deep hole or quarry which may be dug out of the ground ? 

4. What natural channels are provided for the passage of 
water, even through very hard rocks ? 

5. Explain the occurrence of boggy places in hilly ground. 

6. What are Springs ? 

7. Explain why Springs issue from between beds of rock 
along the sides of valleys. 

8. Explain the origin of deep-seated Springs ? 

9. How is the underground Circulation of Water shown by 
wells, mines, and pits ? 

III. The work of Water underground, p. 56. 

1. Does clear Spring-water contain anything else than water ? 
How may this be answered practically ? 

2. What common solutions show that clear transparent water 
may contain a good deal of foreign matter invisible to the eye ? 

3. Whence must the substances dissolved in Spring-water be 
derived ? 

4. What part does Rain play in regard to the purification of 
the Air ? 

5. When a small quantity of town rain is evaporated what 
is left behind. 

6. Whence does Rain-water derive the Carbonic Acid which it 
carries below the soil ? 

7. What effect has water containing carbonic acid on many 
rocks ? 

8. Explain this action of water in limestone countries ? 

9. What is the difference between Hard and Soft Water? 

10. Of what use to Plants and Animals are some of the sub¬ 
stances carried up from below by Spring-water ? 

11. What is the origin of underground tunnels and caverns ? 

IV. How the Surface of the Earth crumbles away, p. 61. 

1. What change usually takes place upon masonry after it 
has been exposed for a time to the air ? 

K 


138 


PHYSICAL GEOGRAPHY. [questions. 


2. Show how a similar change can be observed elsewhere than 
in human erections. 

3. Explain the part taken by Carbonic and Organic Acids in 
the crumbling of the rocks at the surface of the earth. 

4. Explain the effect of the Oxygen in Rain-water upon iron 
and on many rocks ? 

5. Explain the action of Frost in promoting the crumbling of 
soil and the splitting up of rocks. 

6. What is the effect of rapid extremes of heat and cold upon 
rocks ? 

7. How does Wind promote the destruction of rocks ? 

8. State the general result of all these destructive agents upon 
the surface of the land, and show how their action is beneficial 
in making the earth a fit dwelling-place for plants and animals. 

V. What becomes of the Crumbled Parts of Rocks. Hqw 
Soil is made, p. 69. 

1. What is common garden Soil made of? 

2. What is meant by the Chemical Action of Rain ? 

3. Explain the Mechanical Action of Rain. 

4. What is the nature of the process by which Soil is made ? 

5. Why do Soils differ from each other ? 

6. Explain how Soil is continually renewed. 

7. Show how Plants lend their help in the making of Soil. 

8. What part do common Earth-worms play in the same pro¬ 
cess ? 

<>9. In what sense may it be said that the general surface of 
the Land is continually moving towards the Sea ? 

10. How do Brooks and Rivers illustrate the extent to which 
the surface of the Land is mouldering ? 

VI. Brooks and Rivers. Their Origin, p. 74. 

1. Describe the formation of miniature Brooks and Rivers on 
a sloping roadway during a heavy shower of Rain. 

2. Why do Streams flow ? 

3. What are Lakes ? 

4. Why does the Rain run off the surface of the land in Run¬ 
nels, Brooks, and Rivers ? 


questions.] PHYSICAL GEOGRAPHY. 


139 


5. How are the innumerable Brooks of the high ground dis¬ 
posed of as they descend towards the lower country ? 

6. What is meant by a Water-shed or Divide? Give ex¬ 
amples. 

7. Why do large rivers continue to flow even in dry weather ? 

8. Why do small streams often dry up in summer ? 

9. Why are some rivers, such as the Rhine, most swollen in 
iiiunmer ? 

10. Give a brief account of the Circulation of Water over the 
globe. 

VII. Brooks and Rivers. Their Work, p. 81. 

1. Give an illustration of the vast amount of invisible mate¬ 
rial carried, in chemical solution, by a River to the sea. 

2. Why are Rivers discoloured during floods ? 

3. What is the origin of the gravel and blocks of stone in 
the bed of a stream, and why are the stones usually rounded ? 

4. What are Pot-holes ? 

5. How have River-gorges and Ravines been formed ? 

6. Describe the bed of a river when the water is low. 

7. Explain the origin of the flat terraces bordering a river. 

8. Describe a Delta, and show how it may be formed at the 
mouth of a river, in a lake, or in the sea. 

9. Give an example of a large Delta. 

10. What becomes of the Mud and Sand which are carried 
past the delta ? 

11. What is the final destination of the materials worn from 
off the surface of the Land ? 

VIII. Snowfields and Glaciers, p. 88. 

1. What is meant by the Snow-line ? 

2. What is its height at the equator and in the polar regions ? 

3. Why does snow remain perpetual above the Snow-line ? 

4. Mention some points of difference between a shower of 
rain and of snow. 

5. How does snow below the Snow-line disappear ? 

6. What is meant by a Thaw ? 

7. What is the consequence of a rapid thaw ? 


140 


PHYSICAL GEOGRAPHY. [questions. 


8. What becomes of the mass of snow which accumulates 
above the Snow-line ? 

9. Describe the formation of a Glacier. 

10. What becomes of a glacier as it descends its valley ? 

11. What are Moraines ? 

12. How do stones and earth get under the ice of a glacier ? 

13. What use does the glacier make of these stones and par¬ 
ticles of earth and sand ? 

14. Why is the river of water muddy which escapes from the 
end of a glacier ? 

15. Where do the largest glaciers exist ? 

16. Explain the formation of Icebergs. 

17. What proportion of an iceberg appears above water? 

18. What proofs have been found that glaciers once existed 
in countries such as Britain, where they no longer occur ? 

19. How does Snow exercise a beneficial effect on the surface 
of the ground ? 

20. What are Avalanches ? 


THE SEA. 

I. Grouping of Sea and Land. General Features of the 
Sea, p. 101. 

1. What are the proportions of Land and Water on the earth’s 
surface ? How have these been ascertained ? 

2. Mention the broad difference between Sea and Land in the 
way they are distributed over the globe. 

3. On which side of the equator does most of the Land lie ? 

4. What part of the earth’s surface lies in the centre of the 
Land hemisphere ? 

5. What are Continents and Islands ? 

6. What are Oceans ? 

7. What is meant by the Horizon 1 

8. In what familiar respect does the water of the Sea differ 
from that of ordinary springs and rivers ? 

9. What happens when a drop of sea-water is evaporated on 
a piece of glass ? 


questions.] PHYSICAL GEOGRAPHY. 


141 


II. Why the Sea is Salt, p. 106. 

1. What appears to have been the original condition of the 
globe ? 

2. What has been the probable origin of the Atmosphere ? 

3. What has been the probable origin of the Ocean Water ? 

4. From what sources has the mineral matter in sea-water 
come ? 

5. On what grounds may it be inferred that the Sea is slowly 
becoming salter ? 

6. What is the relative saltness of the Atlantic Ocean and the 
Dead Sea ? 

III. The Motions of the Sea, p. 108. 

1. What is the general characteristic of the surface of the Sea ? 

2. Describe what is meant by the Tides. 

3. What is Surface-drift, and how is it often indicated ? 

4. What are Currents in the sea, and how are they sometimes 
made evident ? 

5. How may a basin or trough of water be made to illustrate 
the formation of Waves ? 

6. What is Ground-swell ? 

7. What is the connection between movements of the Air and 
ripples or waves on the Sea ? 

8. What general effect have Waves on the edge of the Land 
exposed to their influence ? 

9. Describe the action of the Sea upon a rocky coast. 

10. What has been the rate of destruction along some parts 
of the east coast of England ? 

11. By what means do Waves wear down hard rocks ? 

12. Explain the process by which gravel and sand are ground 
down by the waves upon the beach. 

IV. The Bottom of the Sea, p. 114. 

1. What is the general character of the Sea-floor ? 

2. How is our information regarding the Bottom of the Deep 
Sea obtained ? 

3. What is the depth of the Atlantic Ocean ? 


142 


PHYSICAL GEOGRAPHY. [questions. 


4. What is the relation between the height of Mont Blanc 
and the depth of the Atlantic Ocean ? 

5. What is the average depth of the Sea ? 

6. Which are usually the deepest and which the shallowest 
parts of the Sea ? 

7. What is the depth of the deeper parts of the North Sea ? 

8. How much of St. Paul’s Cathedral in London would be 
submerged were it placed in the middle of the Straits of Dover ? 

9. What is a Dredge, and what use is made of it 1 

10. What light has been obtained by means of the Dredge 
regarding the living things of the deep sea bottom ? 

11. Mention an important difference between the crumbling 
Land-surface [Arts. 133-147], and the bottom of the Sea. 

12. To what part of the Sea is the destructive action of the 
Waves limited ? 

13. Why must we believe the Floor of the Ocean abysses to 
remain undisturbed. 

14. Where may Banks of Gravel be expected to occur on the 
sea floor ? 

15. In what way is the Sand arranged ? 

16. How is the fine Mud or Silt disposed of ? 

17. Within what average distance from land does the Sedi¬ 
ment derived from the Land subside to the bottom of the Sea ? 

18. What is the nature of the Deposits that cover vast spaces 
of the deeper parts of the sea-bottom, and whence are they 
derived ? 

19. What becomes of the remains of the Shells, Corals, and 
other creatures on the Sea-floor ? 

20. What are Shell-banks ? 

21. What are Coral-reefs and Coral-islands, and how are they 
formed ? 

22. What is the nature of the Ooze which covers a great part 
of the bed of the Atlantic ? 

23. How could you be certain that some Rocks must once have 
been under the Sea ? 

24. What would be the result of the waste of the surface of 
the Land if there were no compensating agency at work ? 


questions.] PHYSICAL GEOGRAPHY. 


143 


THE INSIDE OF THE EARTH, p. 121. 

1. Does the distance from the top of the highest mountain to 
the bottom of the deepest mine bear a large proportion to the 
diameter of the whole Globe ? 

2. What is a Volcano ? 

3. What is a Crater ? 

4. What various materials are thrown out by a Volcano ? 

5. What evidence do these materials furnish as to the condi¬ 
tion of the Earth’s Interior ? 

6. Describe a Volcanic Eruption. 

7. What has been the history of Vesuvius ? 

8. State the position of some of the Volcanoes of Europe, 
America, and Asia. 

9. What evidence do Hot Springs bring to bear upon the state 
of the internal parts of our globe ? 

10. What has been observed regarding Temperature as we 
descend into the Earth, and what inference has been drawn' 
from it ? 

11. Is the solid Earth subject to any movements ? 

12. What are Earthquakes ? Where are they most frequent ? 

13. Mention any facts which show that different parts of the 
Earth’s surface are slowly changing their level. 

14. In what way do the movements of the solid Earth tend to 
counteract the general lowering of level caused by the destruc¬ 
tive action of air, rain, frosts, rivers, glaciers, and the sea ? 

15. How do these movements tend to lower the level of the 
Sea ? 

16. Under what circumstances were the rocks of most of our 
hills and valleys formed ? 


THE END. 


STANDARD TEXT-BOOKS IN 

PHYSIOLOGY AND HYGIENE 


Kellogg’s First Book in Physiology and Hygiene 
Cloth. l 2 mo. 174 pages .... .40 cents 

Kellogg’s Second Book in Physiology and Hygiene 
Cloth, i 2 mo. 291 pages . . . . . 80 cents 

These two books constitute an entirely new and well graded 
series for the study of Physiology and Hygiene in schools. 
The important subjects of sanitation and temperance are thor¬ 
oughly treated from a scientific and physiological standpoint. 

Smith’s Primer of Physiology and Hygiene 
Cloth, i 2 mo. 174 pages . . . . 30 cents 

Smith’s Elementary Physiology and Hygiene 
Cloth, i 2 mo. 225 pages . . . . .50 cents 

A complete and symmetrical series in which the important 
facts of Physiology and Hygiene are presented in an interest¬ 
ing and logical manner. 

Steele’s Hygienic Physiology 

Cloth, i 2 mo. 400 pages ..... $1.00 

The Same —Abridged. Cloth, i 2 mo. 192 pages, 50 cents 
This standard text-book contains all the excellent and popu¬ 
lar features that have given Dr. Steele’s Science Series such 
wide use throughout the country. 

Tracy’s Essentials of Anatomy^ Physiology and Hygiene 
Cloth, i 2 mo. 345 pages . . . $1.00 

A practical and scientific text-book of an advanced grade, 
for use in High Schools, Academies and Normal Schools. 

Johonnot and Bouton’s How We Live 

Cloth, i 2 mo. 178 pages . . . . .40 cents 

An elementary text-book for beginners, giving special 
attention to the laws of hygiene. 

Walker’s Health Lessons 

Cloth, i 2 mo. 194 pages ..... 48 cents 

A book for beginners, presenting the subjects in an interest¬ 
ing and readable form, suitable for supplementary readings. 


Copies of any of the above books zvill be sent prepaid to any 
address , on receipt of the price , by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(S.4) 




Physics 


Appletons’ School Physics 

By John D. Quackenbos, A.M., Alfred M. Mayer, Ph.D., 
Silas W. Holman, S B., Francis E. Nipher, A.M., and 
Francis B. Crocker, E.M. Cloth, i 2 mo. 552 pages, $ 1.20 
A modern text-book in Physics, thoroughly scientific in 
text and treatment, and reflecting the most advanced pedagog¬ 
ical methods and the latest laboratory practice. Adapted for 
use in High Schools, Academies, Normal Schools and Colleges. 

Cooley’s New Text-Book of Physics 

By LeRoy C. Cooley, Ph.D. Cloth, i 2 mo. 327 pp. 90 cents 
An elementary course in Natural Philosophy for High 
Schools and Academies. It is brief, modern, logical in ar¬ 
rangement, and thoroughly systematic. 

Steele’s Popular Physics 

By J. Dorman Steele, Ph.D. Cloth, i 2 mo. 392 pages, $ 1.00 
This new work is a thorough revision of the popular text¬ 
book, “ Fourteen Weeks in Physics,” so long and favorably 
known. It presents the principles of the science in such an 
attractive manner as to awaken and hold the interest of the 
student from the first. 

Stewart’s Physics—Science Primer Series 

By Balfour Stewart. Flexible cloth, i 8 mo. 168 pp. 35 cents 
An exposition of the fundamental principles of Physics 
suited to pupils in elementary grades or for the general reader. 

Trowbridge’s New Physics 

By John Trowbridge, S.D. Cloth, i 2 mo. 387 pages, $ 1.20 
A thoroughly modern work, intended for Colleges and 
advanced Preparatory Schools. 

Hammel’s Observation Blanks in Physics 

By William C. A. Hammel. Flexible, 4 to. 42 pages. 

Illustrated. 30 cents 

A guide and note book for laboratory practice, designed for 
beginners in the study or to accompany any text-book. 


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address, on receipt of the price , by the Publishers: 

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New York ♦ Cincinnati ♦ Chicago 

(S. 5) 




Text-Books in Astronomy 


Bowen> Astronomy by Observation 

By Eliza A. Bowen. Boards, Quarto. Colored maps and 

illustrations. 94 pages.$ 1 X 0 

An elementary text-book for schools, and especially adapted 
for use as an atlas to accompany any other text-book in astron¬ 
omy. Careful directions are given when, how and where to 
find the heavenly bodies, and the quarto pages admit star maps 
and views on a large scale. 

Gillet and Rolfe’s Astronomies 
By J. A. Gillet and W. J. Rolfe. 

First Book in Astronomy. 220 pages . . $1.00 

Astronomy. 415 pages.1.40 

Lockyer’s Astronomies 
By J. N. Lockyer, F.R.S. 

Astronomy. (Science Primer Series.) 136 pages, 35 cents 
Elementary Lessons in Astronomy. 312 pages, $1.22 

Ray’s New Elements of Astronomy 
By Selim H. Peabody, Ph.D., LL.D. 

Cloth, i 2 mo. 352 pages . . . . . $1.20 

Steele’s New Descriptive Astronomy 
By J. Dorrnan Steele, Ph. D. Cloth, i 2 mo. 338 pages, $1.00 
This book supplies an adequate course for all secondary 
schools and college preparatory classes. It conforms to the 
latest discoveries and approved theories of the science. It 
is written in the same interesting and inspiring manner as the 
other books of the Steele Series. 


Copies of any of the above books will be sent prepaid to any 
address , on receipt of the brice, by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

<S.7> 




Geology 


Dana’s Geological Story Briefly Told 
By James D. Dana. 

Cloth, l 2 mo. 302 pages. Illustrated . . , $1.15 

A new edition of this popular work for beginners in the study 
and for the general reader. 

Dana’s New Text Book of Geology 
By James D. Dana. 

Cloth, i 2 mo. 422 pages. Illustrated . . . $2 00 

This standard work has been thoroughly revised and con¬ 
siderably enlarged and freshly illustrated to represent the latest 
demands of the science. 

Dana’s Manual of Geology 
By James D. Dana. 

Cloth, 8 vo. 1087 pages. 1575 illustrations . . $5 00 

Fourth revised edition. This great work was thoroughly 
revised and entirely rewritten under the direct supervision of 
its author, just before his death. It is recognized as a standard 
authority in the science both in Europe and America, and is 
used as a manual of instruction in all the higher institutions of 
learning. 

Le Conte’s Compend of Geology 
By Joseph Le Conte. Cloth, i 2 mo. 399 pages . $1.20 

Steele’s Fourteen Weeks in Geology 
By J. Dorman Steele. Cloth, i 2 mo. 280 pages . $1.00 

Andrews's Elementary Geology 

By E. B. Andrews. Cloth, i 2 mo. 283 pages . $1.00 

Adapted for elementary classes. Contains a special treatment 
of the geology of the Mississippi Valley. 

Nicholson’s Text-Book of Geology 
By H. A. Nicholson. Cloth, i 2 mo. 520 pages . $1.05 

Williams’s Applied Geology 

By S. G. Williams. Cloth, i 2 mo. 386 pages . $1.20 

A treatise on the industrial relations of geological structure; 
and on the nature, occurrence, and uses of substances derived 
from geological sources. 


Copies of any of the above books will be sent prepaid to any 
address, on receipt of the price, by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(S. 8) 




CHEMISTRY 

TEXT-BOOKS AND LABORATORY METHODS 


Storer and Lindsay’s Elementary Manual of Chemistry 
By F. H. Storer and W. B. Lindsay. 

Cloth, i2mo. 453 pages . . . . . $ 1.20 

Brewster’s First Book of Chemistry 
By Mary Shaw-Brewster. Boards, i2mo. 144 pp. 66 cents 

Clarke’s Elements of Chemistry 

By F. W. Clarke. Cloth, i2mo. 379 pages . $ 1.20 

Cooley’s New Elementary Chemistry for Beginners 

By LeRoy C. Cooley. Cloth, i2mo. 300 pages . 72 cents 

Cooley’s New Text-Book of Chemistry 
By LeRoy C. Cooley. Cloth, i2mo. 311 pages . 90 cents 

Steele’s Popular Chemistry 

By J. Dorman Steele. Cloth, i2mo. 343 pages . $ 1.00 

Youmans’s Class Book of Chemistry 

By E. L. Youmans. Revised and edited by W. J. Youmans. 
Cloth, i2mo. 404 pages . . . $ 1.22 


Armstrong and Norton’s Laboratory Manual of Chemistry 
By James E. Armstrong and James Ii. Norton. 

Cloth, i2mo. 144 pages . . . . .50 cents 

Cooley’s Laboratory Studies in Chemistry 

By LeRoy C. Cooley. Cloth, 8vo. 144 pages . 50 cents 

Keiser’s Laboratory Work in Chemistry 
By Edward H. Keiser. Cloth, i2mo. 119 pages . 50 cents 

Qualitative Chemical Analysis of Inorganic Substances 
As practised in Georgetown College, D. C. 

Cloth, 4to. 61 pages.$ 1.50 


Copies of any of the above books will be sent prepaid to any 
address , on receipt of the price , by the Publishers: 

American Book Company 

Mew York ♦ Cincinnati ♦ Chicago 

(S. 9) 





Storer and Lindsay’s 
Elementary Manual of Chemistry 

BY 

F. H. STORER, S.B., A.M., and 
W. B. LINDSAY, A.B., B.S. 

Cloth, i2mo, 453 pages. Illustrated. Price, $1.20 


This work is the lineal descendant of the “ Manual of 
Inorganic Chemistry” of Eliot and Storer, and the “ Element¬ 
ary Manual of Chemistry ” of Eliot, Storer and Nichols. It 
is in fact the last named book thoroughly revised, rewritten 
and enlarged to represent the present condition of chemical 
knowledge and to meet the demands of American teachers for 
a class book on Chemistry, at once scientific in statement and 
clear in method. 

The purpose of the book is to facilitate the study and 
teaching of Chemistry by the experimental and inductive 
method. It presents the leading facts and theories of the 
science in such simple and concise manner that they can be 
readily understood and applied by the student. The book is 
equally valuable in the classroom and the laboratory. The 
instructor will find in it the essentials of chemical science 
developed in easy and appropriate sequence, its facts and 
generalizations expressed accurately and scientifically as well 
as clearly, forcibly and elegantly. 


Copies of Storer and Lindsay's Chemistry will be sent prepaid 
to any address , on receipt of the price , by the Publishers : 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(S .10) 




Standard Text-Books in Botany 


Gray’s How Plants Grow. (Introductory Book) . 80 cents 

Gray’s How Plants Behave . . . .54 tents 

For Beginners in Primary and Intermediate Schools. 

Gray’s Lessons in Botany. (Revised) . . .94 cents 

Gray’s Field, Forest and Garden Botany . . $1.44 

(Flora.) 

Gray’s School and Field Botany . . . . 1.80 

(The Standard Text-Book.) 

For Students in High Schools, Academies and Seminaries. 

Steele’s Fourteen Weeks in Botany . . $1.00 

Wood’s How to Study Plants .... 1.00 

Wood’s Lessons in Botany. (Revised) . . .90 cents 

Wood’s New American Botanist and Florist . . $1.75 

(Revised) 

Wood’s Descriptive Botany.1.25 

Being the Flora of the American Botanist and Florist. 
Wood’s Class Book of Botany .... 2.50 

A standard work for advanced classes and for the Student’s 
Library. 

Youmans’s First Book in Botany . . .64 cents 

Youmans’s Descriptive Botany . . . $1.20 

Bentley’s Physiological Botany . . 1.20 


Dana’s Plants and their Children . .65 cents 

Herrick’s Chapters on Plant Life . . . .60 cents 

Hooker’s Botany. (Science Primer Series) . 35 cents 

Willis’s Practical Flora ...... $1.50 

A valuable supplementary aid to any text-book in the study 
of Botany. 


Copies of any of the above books will be sent prepaid to any 
address . on receipt of the price, by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(S. xi) 







Zoology and Natural History 

Burnet’s Zoology 

By Margaretta Burnet. Cloth, i 2 mo. 216 pages, 75 cents 
A new text-book for High Schools and Academies, by a 
practical teacher; sufficiently elementary for beginners and full 
enough for the usual course in Natural History. 

Needham’s Elementary Lessons in Zoology 
By James G. Needham. Cloth, i 2 mo. 302 pages, 90 cents 
An elementary text-book for High Schools, Academies, 
Normal Schools and Preparatory College Classes. Special 
attention is given to the study by scientific methods, laboratory 
practice, microscopic study and practical zootomy. 

Cooper’s Animal Life 

By Sarah Cooper. Cloth, i 2 mo. 427 pages $1.25 

An attractive book for young people. Admirably adapted 
for supplementary readings in Natural History. 

Holders’ Elementary Zoology 
By C. F. Holder and J. B. Holder, M.D. 

Cloth, i 2 mo. 401 pages.$1.20 

- Hooker’s Natural History 

By Worthington Hooker, M.D. 

Cloth, i 2 mo. 394 pages . . . . .90 cents 

Morse’s First Book in Zoology 
By Edward S. Morse, Ph.D. 

Boards, i 2 mo. 204 pages . . . .87 cents 

Nicholson's Text-Book of Zoology 
By H. A. Nicholson, M.D. Cloth, i 2 mo. 421 pp. $1.38 
Steele’s Popular Zoology 
By J. Dorman Steele and J. W. P. Jenks. 

Cloth, T 2 mo. 369 pages.$1.20 

Tenneys’ Natural History of Animals 

By Sanborn Tenney and Abbey A. Tenney. 

Revised Edition. Cloth, i 2 mo. 281 pages . $1.20 

This new edition has been entirely reset and thoroughly 
revised, the recent changes in classification introduced, and 
the book in all respects brought up to date. 

Treat’s Home Studies in Nature 

By Mrs. Mary Treat. Cloth, i 2 mo. 244 pages, 90 cents 


Copies of any of the above books will be sent prepaid to any 
address , on receipt of the price , by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(S. 12) 




Eclectic English Classics 


The best selections of English Literature in the most con¬ 
venient form and at the lowest prices. 

Arnold’s (Matthew) Sohrab and Rustum . . . . • $ 0.20 

Burke’s Conciliation with the American Colonies . . . .20 

Carlyle’s Essay on Burns.— 

Coleridge’s Rime of the Ancient Mariner .... .20 

Defoe’s History of the Plague in London ..... .40 

DeQ uincey’s Revolt of the Tartars. .20 

Emerson’s American Scholar, Self-Reliance, and Compensation . .20 

Franklin’s Autobiography. .35 

“George Eliot’s” Silas Marner .. .30 

Goldsmith’s Vicar of Wakefield ....... .35 

Irving’s Sketch Book—Selections ....... .20 

Tales of a Traveler ......... .50 

Macaulay’s Second Essay on Chatham ...... .20 

Essay on Milton ......... .20 

Essay on Addison .......... .20 

Life of Samuel Johnson ........ .20 

Milton’s L’Allegro, 11 Penseroso, Comus, and Lycidas . . .20 

Paradise Lost—Books I. and II. ..... .20 

Pope’s Homer’s Iliad—Books I., VI., XXII. and XXIV. . . .20 

Scott’s Ivanhoe. .50 

Marmion. .40 

Lady of the Lake. . 30 

The Abbot ........... .60 

Woodstock ........... .60 

Shakespeare’s Julius Caesar ........ .20 

Twelfth Night .......... .20 

Merchant of Venice ......... .20 

Midsummer-Night’s Dream ....... .20 

As You Like It ......... .20 

Macbeth. .20 

Hamlet .. .25 

Sir Roger de Coverley Papers (The Spectator) . . . .20 

Southey’s Life of Nelson ......... .40 

Tennyson’s Princess ......... .20 

Webster’s Bunker Hill Orations ....... .20 


any address , on receipt of the price , by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(S. 16 ) 







































